--- title: "Bisync" description: "Bidirectional cloud sync solution in rclone" versionIntroduced: "v1.58" --- ## Getting started {#getting-started} - [Install rclone](/install/) and setup your remotes. - Bisync will create its working directory at `~/.cache/rclone/bisync` on Linux or `C:\Users\MyLogin\AppData\Local\rclone\bisync` on Windows. Make sure that this location is writable. - Run bisync with the `--resync` flag, specifying the paths to the local and remote sync directory roots. - For successive sync runs, leave off the `--resync` flag. (**Important!**) - Consider using a [filters file](#filtering) for excluding unnecessary files and directories from the sync. - Consider setting up the [--check-access](#check-access) feature for safety. - On Linux, consider setting up a [crontab entry](#cron). bisync can safely run in concurrent cron jobs thanks to lock files it maintains. Here is a typical run log (with timestamps removed for clarity): ``` rclone bisync /testdir/path1/ /testdir/path2/ --verbose INFO : Synching Path1 "/testdir/path1/" with Path2 "/testdir/path2/" INFO : Path1 checking for diffs INFO : - Path1 File is new - file11.txt INFO : - Path1 File is newer - file2.txt INFO : - Path1 File is newer - file5.txt INFO : - Path1 File is newer - file7.txt INFO : - Path1 File was deleted - file4.txt INFO : - Path1 File was deleted - file6.txt INFO : - Path1 File was deleted - file8.txt INFO : Path1: 7 changes: 1 new, 3 newer, 0 older, 3 deleted INFO : Path2 checking for diffs INFO : - Path2 File is new - file10.txt INFO : - Path2 File is newer - file1.txt INFO : - Path2 File is newer - file5.txt INFO : - Path2 File is newer - file6.txt INFO : - Path2 File was deleted - file3.txt INFO : - Path2 File was deleted - file7.txt INFO : - Path2 File was deleted - file8.txt INFO : Path2: 7 changes: 1 new, 3 newer, 0 older, 3 deleted INFO : Applying changes INFO : - Path1 Queue copy to Path2 - /testdir/path2/file11.txt INFO : - Path1 Queue copy to Path2 - /testdir/path2/file2.txt INFO : - Path2 Queue delete - /testdir/path2/file4.txt NOTICE: - WARNING New or changed in both paths - file5.txt NOTICE: - Path1 Renaming Path1 copy - /testdir/path1/file5.txt..path1 NOTICE: - Path1 Queue copy to Path2 - /testdir/path2/file5.txt..path1 NOTICE: - Path2 Renaming Path2 copy - /testdir/path2/file5.txt..path2 NOTICE: - Path2 Queue copy to Path1 - /testdir/path1/file5.txt..path2 INFO : - Path2 Queue copy to Path1 - /testdir/path1/file6.txt INFO : - Path1 Queue copy to Path2 - /testdir/path2/file7.txt INFO : - Path2 Queue copy to Path1 - /testdir/path1/file1.txt INFO : - Path2 Queue copy to Path1 - /testdir/path1/file10.txt INFO : - Path1 Queue delete - /testdir/path1/file3.txt INFO : - Path2 Do queued copies to - Path1 INFO : - Path1 Do queued copies to - Path2 INFO : - Do queued deletes on - Path1 INFO : - Do queued deletes on - Path2 INFO : Updating listings INFO : Validating listings for Path1 "/testdir/path1/" vs Path2 "/testdir/path2/" INFO : Bisync successful ``` ## Command line syntax ``` $ rclone bisync --help Usage: rclone bisync remote1:path1 remote2:path2 [flags] Positional arguments: Path1, Path2 Local path, or remote storage with ':' plus optional path. Type 'rclone listremotes' for list of configured remotes. Optional Flags: --check-access Ensure expected `RCLONE_TEST` files are found on both Path1 and Path2 filesystems, else abort. --check-filename FILENAME Filename for `--check-access` (default: `RCLONE_TEST`) --check-sync CHOICE Controls comparison of final listings: `true | false | only` (default: true) If set to `only`, bisync will only compare listings from the last run but skip actual sync. --filters-file PATH Read filtering patterns from a file --max-delete PERCENT Safety check on maximum percentage of deleted files allowed. If exceeded, the bisync run will abort. (default: 50%) --force Bypass `--max-delete` safety check and run the sync. Consider using with `--verbose` --create-empty-src-dirs Sync creation and deletion of empty directories. (Not compatible with --remove-empty-dirs) --remove-empty-dirs Remove empty directories at the final cleanup step. -1, --resync Performs the resync run. Warning: Path1 files may overwrite Path2 versions. Consider using `--verbose` or `--dry-run` first. --ignore-listing-checksum Do not use checksums for listings (add --ignore-checksum to additionally skip post-copy checksum checks) --resilient Allow future runs to retry after certain less-serious errors, instead of requiring --resync. Use at your own risk! --localtime Use local time in listings (default: UTC) --no-cleanup Retain working files (useful for troubleshooting and testing). --workdir PATH Use custom working directory (useful for testing). (default: `~/.cache/rclone/bisync`) --backup-dir1 PATH --backup-dir for Path1. Must be a non-overlapping path on the same remote. --backup-dir2 PATH --backup-dir for Path2. Must be a non-overlapping path on the same remote. -n, --dry-run Go through the motions - No files are copied/deleted. -v, --verbose Increases logging verbosity. May be specified more than once for more details. -h, --help help for bisync ``` Arbitrary rclone flags may be specified on the [bisync command line](/commands/rclone_bisync/), for example `rclone bisync ./testdir/path1/ gdrive:testdir/path2/ --drive-skip-gdocs -v -v --timeout 10s` Note that interactions of various rclone flags with bisync process flow has not been fully tested yet. ### Paths Path1 and Path2 arguments may be references to any mix of local directory paths (absolute or relative), UNC paths (`//server/share/path`), Windows drive paths (with a drive letter and `:`) or configured [remotes](/docs/#syntax-of-remote-paths) with optional subdirectory paths. Cloud references are distinguished by having a `:` in the argument (see [Windows support](#windows) below). Path1 and Path2 are treated equally, in that neither has priority for file changes (except during [`--resync`](#resync)), and access efficiency does not change whether a remote is on Path1 or Path2. The listings in bisync working directory (default: `~/.cache/rclone/bisync`) are named based on the Path1 and Path2 arguments so that separate syncs to individual directories within the tree may be set up, e.g.: `path_to_local_tree..dropbox_subdir.lst`. Any empty directories after the sync on both the Path1 and Path2 filesystems are not deleted by default, unless `--create-empty-src-dirs` is specified. If the `--remove-empty-dirs` flag is specified, then both paths will have ALL empty directories purged as the last step in the process. ## Command-line flags #### --resync This will effectively make both Path1 and Path2 filesystems contain a matching superset of all files. Path2 files that do not exist in Path1 will be copied to Path1, and the process will then copy the Path1 tree to Path2. The `--resync` sequence is roughly equivalent to: ``` rclone copy Path2 Path1 --ignore-existing [--create-empty-src-dirs] rclone copy Path1 Path2 [--create-empty-src-dirs] ``` The base directories on both Path1 and Path2 filesystems must exist or bisync will fail. This is required for safety - that bisync can verify that both paths are valid. When using `--resync`, a newer version of a file on the Path2 filesystem will be overwritten by the Path1 filesystem version. (Note that this is [NOT entirely symmetrical](https://github.com/rclone/rclone/issues/5681#issuecomment-938761815).) Carefully evaluate deltas using [--dry-run](/flags/#non-backend-flags). For a resync run, one of the paths may be empty (no files in the path tree). The resync run should result in files on both paths, else a normal non-resync run will fail. For a non-resync run, either path being empty (no files in the tree) fails with `Empty current PathN listing. Cannot sync to an empty directory: X.pathN.lst` This is a safety check that an unexpected empty path does not result in deleting **everything** in the other path. **Note:** `--resync` should only be used under three specific (rare) circumstances: 1. It is your _first_ bisync run (between these two paths) 2. You've just made changes to your bisync settings (such as editing the contents of your `--filters-file`) 3. There was an error on the prior run, and as a result, bisync now requires `--resync` to recover The rest of the time, you should _omit_ `--resync`. The reason is because `--resync` will only _copy_ (not _sync_) each side to the other. Therefore, if you included `--resync` for every bisync run, it would never be possible to delete a file -- the deleted file would always keep reappearing at the end of every run (because it's being copied from the other side where it still exists). Similarly, renaming a file would always result in a duplicate copy (both old and new name) on both sides. #### --check-access Access check files are an additional safety measure against data loss. bisync will ensure it can find matching `RCLONE_TEST` files in the same places in the Path1 and Path2 filesystems. `RCLONE_TEST` files are not generated automatically. For `--check-access` to succeed, you must first either: **A)** Place one or more `RCLONE_TEST` files in both systems, or **B)** Set `--check-filename` to a filename already in use in various locations throughout your sync'd fileset. Recommended methods for **A)** include: * `rclone touch Path1/RCLONE_TEST` (create a new file) * `rclone copyto Path1/RCLONE_TEST Path2/RCLONE_TEST` (copy an existing file) * `rclone copy Path1/RCLONE_TEST Path2/RCLONE_TEST --include "RCLONE_TEST"` (copy multiple files at once, recursively) * create the files manually (outside of rclone) * run `bisync` once *without* `--check-access` to set matching files on both filesystems will also work, but is not preferred, due to potential for user error (you are temporarily disabling the safety feature). Note that `--check-access` is still enforced on `--resync`, so `bisync --resync --check-access` will not work as a method of initially setting the files (this is to ensure that bisync can't [inadvertently circumvent its own safety switch](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=3.%20%2D%2Dcheck%2Daccess%20doesn%27t%20always%20fail%20when%20it%20should).) Time stamps and file contents for `RCLONE_TEST` files are not important, just the names and locations. If you have symbolic links in your sync tree it is recommended to place `RCLONE_TEST` files in the linked-to directory tree to protect against bisync assuming a bunch of deleted files if the linked-to tree should not be accessible. See also the [--check-filename](--check-filename) flag. #### --check-filename Name of the file(s) used in access health validation. The default `--check-filename` is `RCLONE_TEST`. One or more files having this filename must exist, synchronized between your source and destination filesets, in order for `--check-access` to succeed. See [--check-access](#check-access) for additional details. #### --max-delete As a safety check, if greater than the `--max-delete` percent of files were deleted on either the Path1 or Path2 filesystem, then bisync will abort with a warning message, without making any changes. The default `--max-delete` is `50%`. One way to trigger this limit is to rename a directory that contains more than half of your files. This will appear to bisync as a bunch of deleted files and a bunch of new files. This safety check is intended to block bisync from deleting all of the files on both filesystems due to a temporary network access issue, or if the user had inadvertently deleted the files on one side or the other. To force the sync, either set a different delete percentage limit, e.g. `--max-delete 75` (allows up to 75% deletion), or use `--force` to bypass the check. Also see the [all files changed](#all-files-changed) check. #### --filters-file {#filters-file} By using rclone filter features you can exclude file types or directory sub-trees from the sync. See the [bisync filters](#filtering) section and generic [--filter-from](/filtering/#filter-from-read-filtering-patterns-from-a-file) documentation. An [example filters file](#example-filters-file) contains filters for non-allowed files for synching with Dropbox. If you make changes to your filters file then bisync requires a run with `--resync`. This is a safety feature, which prevents existing files on the Path1 and/or Path2 side from seeming to disappear from view (since they are excluded in the new listings), which would fool bisync into seeing them as deleted (as compared to the prior run listings), and then bisync would proceed to delete them for real. To block this from happening, bisync calculates an MD5 hash of the filters file and stores the hash in a `.md5` file in the same place as your filters file. On the next run with `--filters-file` set, bisync re-calculates the MD5 hash of the current filters file and compares it to the hash stored in the `.md5` file. If they don't match, the run aborts with a critical error and thus forces you to do a `--resync`, likely avoiding a disaster. #### --check-sync Enabled by default, the check-sync function checks that all of the same files exist in both the Path1 and Path2 history listings. This _check-sync_ integrity check is performed at the end of the sync run by default. Any untrapped failing copy/deletes between the two paths might result in differences between the two listings and in the untracked file content differences between the two paths. A resync run would correct the error. Note that the default-enabled integrity check locally executes a load of both the final Path1 and Path2 listings, and thus adds to the run time of a sync. Using `--check-sync=false` will disable it and may significantly reduce the sync run times for very large numbers of files. The check may be run manually with `--check-sync=only`. It runs only the integrity check and terminates without actually synching. Note that currently, `--check-sync` **only checks filenames and NOT modtime, size, or hash.** For a more robust integrity check of the current state, consider using [`check`](commands/rclone_check/) (or [`cryptcheck`](/commands/rclone_cryptcheck/), if at least one path is a `crypt` remote.) For example, a possible sequence could look like this: 1. Normally scheduled bisync run: ``` rclone bisync Path1 Path2 -MPc --check-access --max-delete 10 --filters-file /path/to/filters.txt -v --no-cleanup --ignore-listing-checksum --disable ListR --checkers=16 --drive-pacer-min-sleep=10ms --create-empty-src-dirs --resilient ``` 2. Periodic independent integrity check (perhaps scheduled nightly or weekly): ``` rclone check -MvPc Path1 Path2 --filter-from /path/to/filters.txt ``` 3. If diffs are found, you have some choices to correct them. If one side is more up-to-date and you want to make the other side match it, you could run: ``` rclone sync Path1 Path2 --filter-from /path/to/filters.txt --create-empty-src-dirs -MPc -v ``` (or switch Path1 and Path2 to make Path2 the source-of-truth) Or, if neither side is totally up-to-date, you could run a `--resync` to bring them back into agreement (but remember that this could cause deleted files to re-appear.) *Note also that `rclone check` does not currently include empty directories, so if you want to know if any empty directories are out of sync, consider alternatively running the above `rclone sync` command with `--dry-run` added. See also: [Concurrent modifications](#concurrent-modifications), [`--resilient`](#resilient) #### --ignore-listing-checksum By default, bisync will retrieve (or generate) checksums (for backends that support them) when creating the listings for both paths, and store the checksums in the listing files. `--ignore-listing-checksum` will disable this behavior, which may speed things up considerably, especially on backends (such as [local](/local/)) where hashes must be computed on the fly instead of retrieved. Please note the following: * While checksums are (by default) generated and stored in the listing files, they are NOT currently used for determining diffs (deltas). It is anticipated that full checksum support will be added in a future version. * `--ignore-listing-checksum` is NOT the same as [`--ignore-checksum`](/docs/#ignore-checksum), and you may wish to use one or the other, or both. In a nutshell: `--ignore-listing-checksum` controls whether checksums are considered when scanning for diffs, while `--ignore-checksum` controls whether checksums are considered during the copy/sync operations that follow, if there ARE diffs. * Unless `--ignore-listing-checksum` is passed, bisync currently computes hashes for one path *even when there's no common hash with the other path* (for example, a [crypt](/crypt/#modification-times-and-hashes) remote.) #### --resilient ***Caution: this is an experimental feature. Use at your own risk!*** By default, most errors or interruptions will cause bisync to abort and require [`--resync`](#resync) to recover. This is a safety feature, to prevent bisync from running again until a user checks things out. However, in some cases, bisync can go too far and enforce a lockout when one isn't actually necessary, like for certain less-serious errors that might resolve themselves on the next run. When `--resilient` is specified, bisync tries its best to recover and self-correct, and only requires `--resync` as a last resort when a human's involvement is absolutely necessary. The intended use case is for running bisync as a background process (such as via scheduled [cron](#cron)). When using `--resilient` mode, bisync will still report the error and abort, however it will not lock out future runs -- allowing the possibility of retrying at the next normally scheduled time, without requiring a `--resync` first. Examples of such retryable errors include access test failures, missing listing files, and filter change detections. These safety features will still prevent the *current* run from proceeding -- the difference is that if conditions have improved by the time of the *next* run, that next run will be allowed to proceed. Certain more serious errors will still enforce a `--resync` lockout, even in `--resilient` mode, to prevent data loss. Behavior of `--resilient` may change in a future version. #### --backup-dir1 and --backup-dir2 As of `v1.65`, [`--backup-dir`](/docs/#backup-dir-dir) is supported in bisync. Because `--backup-dir` must be a non-overlapping path on the same remote, Bisync has introduced new `--backup-dir1` and `--backup-dir2` flags to support separate backup-dirs for `Path1` and `Path2` (bisyncing between different remotes with `--backup-dir` would not otherwise be possible.) `--backup-dir1` and `--backup-dir2` can use different remotes from each other, but `--backup-dir1` must use the same remote as `Path1`, and `--backup-dir2` must use the same remote as `Path2`. Each backup directory must not overlap its respective bisync Path without being excluded by a filter rule. The standard `--backup-dir` will also work, if both paths use the same remote (but note that deleted files from both paths would be mixed together in the same dir). If either `--backup-dir1` and `--backup-dir2` are set, they will override `--backup-dir`. Example: ``` rclone bisync /Users/someuser/some/local/path/Bisync gdrive:Bisync --backup-dir1 /Users/someuser/some/local/path/BackupDir --backup-dir2 gdrive:BackupDir --suffix -2023-08-26 --suffix-keep-extension --check-access --max-delete 10 --filters-file /Users/someuser/some/local/path/bisync_filters.txt --no-cleanup --ignore-listing-checksum --checkers=16 --drive-pacer-min-sleep=10ms --create-empty-src-dirs --resilient -MvP --drive-skip-gdocs --fix-case ``` In this example, if the user deletes a file in `/Users/someuser/some/local/path/Bisync`, bisync will propagate the delete to the other side by moving the corresponding file from `gdrive:Bisync` to `gdrive:BackupDir`. If the user deletes a file from `gdrive:Bisync`, bisync moves it from `/Users/someuser/some/local/path/Bisync` to `/Users/someuser/some/local/path/BackupDir`. In the event of a `..path1` / `..path2` rename due to a sync conflict, the rename is not considered a delete, unless a previous conflict with the same name already exists and would get overwritten. See also: [`--suffix`](/docs/#suffix-suffix), [`--suffix-keep-extension`](/docs/#suffix-keep-extension) ## Operation ### Runtime flow details bisync retains the listings of the `Path1` and `Path2` filesystems from the prior run. On each successive run it will: - list files on `path1` and `path2`, and check for changes on each side. Changes include `New`, `Newer`, `Older`, and `Deleted` files. - Propagate changes on `path1` to `path2`, and vice-versa. ### Safety measures - Lock file prevents multiple simultaneous runs when taking a while. This can be particularly useful if bisync is run by cron scheduler. - Handle change conflicts non-destructively by creating `..path1` and `..path2` file versions. - File system access health check using `RCLONE_TEST` files (see the `--check-access` flag). - Abort on excessive deletes - protects against a failed listing being interpreted as all the files were deleted. See the `--max-delete` and `--force` flags. - If something evil happens, bisync goes into a safe state to block damage by later runs. (See [Error Handling](#error-handling)) ### Normal sync checks Type | Description | Result | Implementation --------------|-----------------------------------------------|--------------------------|----------------------------- Path2 new | File is new on Path2, does not exist on Path1 | Path2 version survives | `rclone copy` Path2 to Path1 Path2 newer | File is newer on Path2, unchanged on Path1 | Path2 version survives | `rclone copy` Path2 to Path1 Path2 deleted | File is deleted on Path2, unchanged on Path1 | File is deleted | `rclone delete` Path1 Path1 new | File is new on Path1, does not exist on Path2 | Path1 version survives | `rclone copy` Path1 to Path2 Path1 newer | File is newer on Path1, unchanged on Path2 | Path1 version survives | `rclone copy` Path1 to Path2 Path1 older | File is older on Path1, unchanged on Path2 | _Path1 version survives_ | `rclone copy` Path1 to Path2 Path2 older | File is older on Path2, unchanged on Path1 | _Path2 version survives_ | `rclone copy` Path2 to Path1 Path1 deleted | File no longer exists on Path1 | File is deleted | `rclone delete` Path2 ### Unusual sync checks Type | Description | Result | Implementation --------------------------------|---------------------------------------|------------------------------------|----------------------- Path1 new/changed AND Path2 new/changed AND Path1 == Path2 | File is new/changed on Path1 AND new/changed on Path2 AND Path1 version is currently identical to Path2 | No change | None Path1 new AND Path2 new | File is new on Path1 AND new on Path2 (and Path1 version is NOT identical to Path2) | Files renamed to _Path1 and _Path2 | `rclone copy` _Path2 file to Path1, `rclone copy` _Path1 file to Path2 Path2 newer AND Path1 changed | File is newer on Path2 AND also changed (newer/older/size) on Path1 (and Path1 version is NOT identical to Path2) | Files renamed to _Path1 and _Path2 | `rclone copy` _Path2 file to Path1, `rclone copy` _Path1 file to Path2 Path2 newer AND Path1 deleted | File is newer on Path2 AND also deleted on Path1 | Path2 version survives | `rclone copy` Path2 to Path1 Path2 deleted AND Path1 changed | File is deleted on Path2 AND changed (newer/older/size) on Path1 | Path1 version survives |`rclone copy` Path1 to Path2 Path1 deleted AND Path2 changed | File is deleted on Path1 AND changed (newer/older/size) on Path2 | Path2 version survives | `rclone copy` Path2 to Path1 As of `rclone v1.64`, bisync is now better at detecting *false positive* sync conflicts, which would previously have resulted in unnecessary renames and duplicates. Now, when bisync comes to a file that it wants to rename (because it is new/changed on both sides), it first checks whether the Path1 and Path2 versions are currently *identical* (using the same underlying function as [`check`](commands/rclone_check/).) If bisync concludes that the files are identical, it will skip them and move on. Otherwise, it will create renamed `..Path1` and `..Path2` duplicates, as before. This behavior also [improves the experience of renaming directories](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=Renamed%20directories), as a `--resync` is no longer required, so long as the same change has been made on both sides. ### All files changed check {#all-files-changed} If _all_ prior existing files on either of the filesystems have changed (e.g. timestamps have changed due to changing the system's timezone) then bisync will abort without making any changes. Any new files are not considered for this check. You could use `--force` to force the sync (whichever side has the changed timestamp files wins). Alternately, a `--resync` may be used (Path1 versions will be pushed to Path2). Consider the situation carefully and perhaps use `--dry-run` before you commit to the changes. ### Modification times Bisync relies on file timestamps to identify changed files and will _refuse_ to operate if backend lacks the modification time support. If you or your application should change the content of a file without changing the modification time then bisync will _not_ notice the change, and thus will not copy it to the other side. Note that on some cloud storage systems it is not possible to have file timestamps that match _precisely_ between the local and other filesystems. Bisync's approach to this problem is by tracking the changes on each side _separately_ over time with a local database of files in that side then applying the resulting changes on the other side. ### Error handling {#error-handling} Certain bisync critical errors, such as file copy/move failing, will result in a bisync lockout of following runs. The lockout is asserted because the sync status and history of the Path1 and Path2 filesystems cannot be trusted, so it is safer to block any further changes until someone checks things out. The recovery is to do a `--resync` again. It is recommended to use `--resync --dry-run --verbose` initially and _carefully_ review what changes will be made before running the `--resync` without `--dry-run`. Most of these events come up due to an error status from an internal call. On such a critical error the `{...}.path1.lst` and `{...}.path2.lst` listing files are renamed to extension `.lst-err`, which blocks any future bisync runs (since the normal `.lst` files are not found). Bisync keeps them under `bisync` subdirectory of the rclone cache directory, typically at `${HOME}/.cache/rclone/bisync/` on Linux. Some errors are considered temporary and re-running the bisync is not blocked. The _critical return_ blocks further bisync runs. See also: [`--resilient`](#resilient) ### Lock file When bisync is running, a lock file is created in the bisync working directory, typically at `~/.cache/rclone/bisync/PATH1..PATH2.lck` on Linux. If bisync should crash or hang, the lock file will remain in place and block any further runs of bisync _for the same paths_. Delete the lock file as part of debugging the situation. The lock file effectively blocks follow-on (e.g., scheduled by _cron_) runs when the prior invocation is taking a long time. The lock file contains _PID_ of the blocking process, which may help in debug. **Note** that while concurrent bisync runs are allowed, _be very cautious_ that there is no overlap in the trees being synched between concurrent runs, lest there be replicated files, deleted files and general mayhem. ### Return codes `rclone bisync` returns the following codes to calling program: - `0` on a successful run, - `1` for a non-critical failing run (a rerun may be successful), - `2` for a critically aborted run (requires a `--resync` to recover). ## Limitations ### Supported backends Bisync is considered _BETA_ and has been tested with the following backends: - Local filesystem - Google Drive - Dropbox - OneDrive - S3 - SFTP - Yandex Disk It has not been fully tested with other services yet. If it works, or sorta works, please let us know and we'll update the list. Run the test suite to check for proper operation as described below. First release of `rclone bisync` requires that underlying backend supports the modification time feature and will refuse to run otherwise. This limitation will be lifted in a future `rclone bisync` release. ### Concurrent modifications When using **Local, FTP or SFTP** remotes with [`--inplace`](/docs/#inplace), rclone does not create _temporary_ files at the destination when copying, and thus if the connection is lost the created file may be corrupt, which will likely propagate back to the original path on the next sync, resulting in data loss. It is therefore recommended to _omit_ `--inplace`. Files that **change during** a bisync run may result in data loss. Prior to `rclone v1.65`, this was commonly seen in highly dynamic environments, where the filesystem was getting hammered by running processes during the sync. As of `rclone v1.65`, bisync was redesigned to use a "snapshot" model, greatly reducing the risks from changes during a sync. Changes that are not detected during the current sync will now be detected during the following sync, and will no longer cause the entire run to throw a critical error. There is additionally a mechanism to mark files as needing to be internally rechecked next time, for added safety. It should therefore no longer be necessary to sync only at quiet times -- however, note that an error can still occur if a file happens to change at the exact moment it's being read/written by bisync (same as would happen in `rclone sync`.) (See also: [`--ignore-checksum`](https://rclone.org/docs/#ignore-checksum), [`--local-no-check-updated`](https://rclone.org/local/#local-no-check-updated)) ### Empty directories By default, new/deleted empty directories on one path are _not_ propagated to the other side. This is because bisync (and rclone) natively works on files, not directories. However, this can be changed with the `--create-empty-src-dirs` flag, which works in much the same way as in [`sync`](/commands/rclone_sync/) and [`copy`](/commands/rclone_copy/). When used, empty directories created or deleted on one side will also be created or deleted on the other side. The following should be noted: * `--create-empty-src-dirs` is not compatible with `--remove-empty-dirs`. Use only one or the other (or neither). * It is not recommended to switch back and forth between `--create-empty-src-dirs` and the default (no `--create-empty-src-dirs`) without running `--resync`. This is because it may appear as though all directories (not just the empty ones) were created/deleted, when actually you've just toggled between making them visible/invisible to bisync. It looks scarier than it is, but it's still probably best to stick to one or the other, and use `--resync` when you need to switch. ### Renamed directories By default, renaming a folder on the Path1 side results in deleting all files on the Path2 side and then copying all files again from Path1 to Path2. Bisync sees this as all files in the old directory name as deleted and all files in the new directory name as new. A recommended solution is to use [`--track-renames`](/docs/#track-renames), which is now supported in bisync as of `rclone v1.65`. Note that `--track-renames` is not available during `--resync`, as `--resync` does not delete anything (`--track-renames` only supports `sync`, not `copy`.) Otherwise, the most effective and efficient method of renaming a directory is to rename it to the same name on both sides. (As of `rclone v1.64`, a `--resync` is no longer required after doing so, as bisync will automatically detect that Path1 and Path2 are in agreement.) ### `--fast-list` used by default Unlike most other rclone commands, bisync uses [`--fast-list`](/docs/#fast-list) by default, for backends that support it. In many cases this is desirable, however, there are some scenarios in which bisync could be faster *without* `--fast-list`, and there is also a [known issue concerning Google Drive users with many empty directories](https://github.com/rclone/rclone/commit/cbf3d4356135814921382dd3285d859d15d0aa77). For now, the recommended way to avoid using `--fast-list` is to add `--disable ListR` to all bisync commands. The default behavior may change in a future version. ### Overridden Configs When rclone detects an overridden config, it adds a suffix like `{ABCDE}` on the fly to the internal name of the remote. Bisync follows suit by including this suffix in its listing filenames. However, this suffix does not necessarily persist from run to run, especially if different flags are provided. So if next time the suffix assigned is `{FGHIJ}`, bisync will get confused, because it's looking for a listing file with `{FGHIJ}`, when the file it wants has `{ABCDE}`. As a result, it throws `Bisync critical error: cannot find prior Path1 or Path2 listings, likely due to critical error on prior run` and refuses to run again until the user runs a `--resync` (unless using `--resilient`). The best workaround at the moment is to set any backend-specific flags in the [config file](/commands/rclone_config/) instead of specifying them with command flags. (You can still override them as needed for other rclone commands.) ### Case (and unicode) sensitivity {#case-sensitivity} As of `v1.65`, case and unicode form differences no longer cause critical errors, and normalization (when comparing between filesystems) is handled according to the same flags and defaults as `rclone sync`. See the following options (all of which are supported by bisync) to control this behavior more granularly: - [`--fix-case`](/docs/#fix-case) - [`--ignore-case-sync`](/docs/#ignore-case-sync) - [`--no-unicode-normalization`](/docs/#no-unicode-normalization) - [`--local-unicode-normalization`](/local/#local-unicode-normalization) and [`--local-case-sensitive`](/local/#local-case-sensitive) (caution: these are normally not what you want.) Note that in the (probably rare) event that `--fix-case` is used AND a file is new/changed on both sides AND the checksums match AND the filename case does not match, the Path1 filename is considered the winner, for the purposes of `--fix-case` (Path2 will be renamed to match it). ## Windows support {#windows} Bisync has been tested on Windows 8.1, Windows 10 Pro 64-bit and on Windows GitHub runners. Drive letters are allowed, including drive letters mapped to network drives (`rclone bisync J:\localsync GDrive:`). If a drive letter is omitted, the shell current drive is the default. Drive letters are a single character follows by `:`, so cloud names must be more than one character long. Absolute paths (with or without a drive letter), and relative paths (with or without a drive letter) are supported. Working directory is created at `C:\Users\MyLogin\AppData\Local\rclone\bisync`. Note that bisync output may show a mix of forward `/` and back `\` slashes. Be careful of case independent directory and file naming on Windows vs. case dependent Linux ## Filtering {#filtering} See [filtering documentation](/filtering/) for how filter rules are written and interpreted. Bisync's [`--filters-file`](#filters-file) flag slightly extends the rclone's [--filter-from](/filtering/#filter-from-read-filtering-patterns-from-a-file) filtering mechanism. For a given bisync run you may provide _only one_ `--filters-file`. The `--include*`, `--exclude*`, and `--filter` flags are also supported. ### How to filter directories Filtering portions of the directory tree is a critical feature for synching. Examples of directory trees (always beneath the Path1/Path2 root level) you may want to exclude from your sync: - Directory trees containing only software build intermediate files. - Directory trees containing application temporary files and data such as the Windows `C:\Users\MyLogin\AppData\` tree. - Directory trees containing files that are large, less important, or are getting thrashed continuously by ongoing processes. On the other hand, there may be only select directories that you actually want to sync, and exclude all others. See the [Example include-style filters for Windows user directories](#include-filters) below. ### Filters file writing guidelines 1. Begin with excluding directory trees: - e.g. `- /AppData/` - `**` on the end is not necessary. Once a given directory level is excluded then everything beneath it won't be looked at by rclone. - Exclude such directories that are unneeded, are big, dynamically thrashed, or where there may be access permission issues. - Excluding such dirs first will make rclone operations (much) faster. - Specific files may also be excluded, as with the Dropbox exclusions example below. 2. Decide if it's easier (or cleaner) to: - Include select directories and therefore _exclude everything else_ -- or -- - Exclude select directories and therefore _include everything else_ 3. Include select directories: - Add lines like: `+ /Documents/PersonalFiles/**` to select which directories to include in the sync. - `**` on the end specifies to include the full depth of the specified tree. - With Include-style filters, files at the Path1/Path2 root are not included. They may be included with `+ /*`. - Place RCLONE_TEST files within these included directory trees. They will only be looked for in these directory trees. - Finish by excluding everything else by adding `- **` at the end of the filters file. - Disregard step 4. 4. Exclude select directories: - Add more lines like in step 1. For example: `-/Desktop/tempfiles/`, or `- /testdir/`. Again, a `**` on the end is not necessary. - Do _not_ add a `- **` in the file. Without this line, everything will be included that has not been explicitly excluded. - Disregard step 3. A few rules for the syntax of a filter file expanding on [filtering documentation](/filtering/): - Lines may start with spaces and tabs - rclone strips leading whitespace. - If the first non-whitespace character is a `#` then the line is a comment and will be ignored. - Blank lines are ignored. - The first non-whitespace character on a filter line must be a `+` or `-`. - Exactly 1 space is allowed between the `+/-` and the path term. - Only forward slashes (`/`) are used in path terms, even on Windows. - The rest of the line is taken as the path term. Trailing whitespace is taken literally, and probably is an error. ### Example include-style filters for Windows user directories {#include-filters} This Windows _include-style_ example is based on the sync root (Path1) set to `C:\Users\MyLogin`. The strategy is to select specific directories to be synched with a network drive (Path2). - `- /AppData/` excludes an entire tree of Windows stored stuff that need not be synched. In my case, AppData has >11 GB of stuff I don't care about, and there are some subdirectories beneath AppData that are not accessible to my user login, resulting in bisync critical aborts. - Windows creates cache files starting with both upper and lowercase `NTUSER` at `C:\Users\MyLogin`. These files may be dynamic, locked, and are generally _don't care_. - There are just a few directories with _my_ data that I do want synched, in the form of `+ /`. By selecting only the directory trees I want to avoid the dozen plus directories that various apps make at `C:\Users\MyLogin\Documents`. - Include files in the root of the sync point, `C:\Users\MyLogin`, by adding the `+ /*` line. - This is an Include-style filters file, therefore it ends with `- **` which excludes everything not explicitly included. ``` - /AppData/ - NTUSER* - ntuser* + /Documents/Family/** + /Documents/Sketchup/** + /Documents/Microcapture_Photo/** + /Documents/Microcapture_Video/** + /Desktop/** + /Pictures/** + /* - ** ``` Note also that Windows implements several "library" links such as `C:\Users\MyLogin\My Documents\My Music` pointing to `C:\Users\MyLogin\Music`. rclone sees these as links, so you must add `--links` to the bisync command line if you which to follow these links. I find that I get permission errors in trying to follow the links, so I don't include the rclone `--links` flag, but then you get lots of `Can't follow symlink…` noise from rclone about not following the links. This noise can be quashed by adding `--quiet` to the bisync command line. ## Example exclude-style filters files for use with Dropbox {#exclude-filters} - Dropbox disallows synching the listed temporary and configuration/data files. The `- ` filters exclude these files where ever they may occur in the sync tree. Consider adding similar exclusions for file types you don't need to sync, such as core dump and software build files. - bisync testing creates `/testdir/` at the top level of the sync tree, and usually deletes the tree after the test. If a normal sync should run while the `/testdir/` tree exists the `--check-access` phase may fail due to unbalanced RCLONE_TEST files. The `- /testdir/` filter blocks this tree from being synched. You don't need this exclusion if you are not doing bisync development testing. - Everything else beneath the Path1/Path2 root will be synched. - RCLONE_TEST files may be placed anywhere within the tree, including the root. ### Example filters file for Dropbox {#example-filters-file} ``` # Filter file for use with bisync # See https://rclone.org/filtering/ for filtering rules # NOTICE: If you make changes to this file you MUST do a --resync run. # Run with --dry-run to see what changes will be made. # Dropbox won't sync some files so filter them away here. # See https://help.dropbox.com/installs-integrations/sync-uploads/files-not-syncing - .dropbox.attr - ~*.tmp - ~$* - .~* - desktop.ini - .dropbox # Used for bisync testing, so excluded from normal runs - /testdir/ # Other example filters #- /TiBU/ #- /Photos/ ``` ### How --check-access handles filters At the start of a bisync run, listings are gathered for Path1 and Path2 while using the user's `--filters-file`. During the check access phase, bisync scans these listings for `RCLONE_TEST` files. Any `RCLONE_TEST` files hidden by the `--filters-file` are _not_ in the listings and thus not checked during the check access phase. ## Troubleshooting {#troubleshooting} ### Reading bisync logs Here are two normal runs. The first one has a newer file on the remote. The second has no deltas between local and remote. ``` 2021/05/16 00:24:38 INFO : Synching Path1 "/path/to/local/tree/" with Path2 "dropbox:/" 2021/05/16 00:24:38 INFO : Path1 checking for diffs 2021/05/16 00:24:38 INFO : - Path1 File is new - file.txt 2021/05/16 00:24:38 INFO : Path1: 1 changes: 1 new, 0 newer, 0 older, 0 deleted 2021/05/16 00:24:38 INFO : Path2 checking for diffs 2021/05/16 00:24:38 INFO : Applying changes 2021/05/16 00:24:38 INFO : - Path1 Queue copy to Path2 - dropbox:/file.txt 2021/05/16 00:24:38 INFO : - Path1 Do queued copies to - Path2 2021/05/16 00:24:38 INFO : Updating listings 2021/05/16 00:24:38 INFO : Validating listings for Path1 "/path/to/local/tree/" vs Path2 "dropbox:/" 2021/05/16 00:24:38 INFO : Bisync successful 2021/05/16 00:36:52 INFO : Synching Path1 "/path/to/local/tree/" with Path2 "dropbox:/" 2021/05/16 00:36:52 INFO : Path1 checking for diffs 2021/05/16 00:36:52 INFO : Path2 checking for diffs 2021/05/16 00:36:52 INFO : No changes found 2021/05/16 00:36:52 INFO : Updating listings 2021/05/16 00:36:52 INFO : Validating listings for Path1 "/path/to/local/tree/" vs Path2 "dropbox:/" 2021/05/16 00:36:52 INFO : Bisync successful ``` ### Dry run oddity The `--dry-run` messages may indicate that it would try to delete some files. For example, if a file is new on Path2 and does not exist on Path1 then it would normally be copied to Path1, but with `--dry-run` enabled those copies don't happen, which leads to the attempted delete on Path2, blocked again by --dry-run: `... Not deleting as --dry-run`. This whole confusing situation is an artifact of the `--dry-run` flag. Scrutinize the proposed deletes carefully, and if the files would have been copied to Path1 then the threatened deletes on Path2 may be disregarded. ### Retries Rclone has built-in retries. If you run with `--verbose` you'll see error and retry messages such as shown below. This is usually not a bug. If at the end of the run, you see `Bisync successful` and not `Bisync critical error` or `Bisync aborted` then the run was successful, and you can ignore the error messages. The following run shows an intermittent fail. Lines _5_ and _6- are low-level messages. Line _6_ is a bubbled-up _warning_ message, conveying the error. Rclone normally retries failing commands, so there may be numerous such messages in the log. Since there are no final error/warning messages on line _7_, rclone has recovered from failure after a retry, and the overall sync was successful. ``` 1: 2021/05/14 00:44:12 INFO : Synching Path1 "/path/to/local/tree" with Path2 "dropbox:" 2: 2021/05/14 00:44:12 INFO : Path1 checking for diffs 3: 2021/05/14 00:44:12 INFO : Path2 checking for diffs 4: 2021/05/14 00:44:12 INFO : Path2: 113 changes: 22 new, 0 newer, 0 older, 91 deleted 5: 2021/05/14 00:44:12 ERROR : /path/to/local/tree/objects/af: error listing: unexpected end of JSON input 6: 2021/05/14 00:44:12 NOTICE: WARNING listing try 1 failed. - dropbox: 7: 2021/05/14 00:44:12 INFO : Bisync successful ``` This log shows a _Critical failure_ which requires a `--resync` to recover from. See the [Runtime Error Handling](#error-handling) section. ``` 2021/05/12 00:49:40 INFO : Google drive root '': Waiting for checks to finish 2021/05/12 00:49:40 INFO : Google drive root '': Waiting for transfers to finish 2021/05/12 00:49:40 INFO : Google drive root '': not deleting files as there were IO errors 2021/05/12 00:49:40 ERROR : Attempt 3/3 failed with 3 errors and: not deleting files as there were IO errors 2021/05/12 00:49:40 ERROR : Failed to sync: not deleting files as there were IO errors 2021/05/12 00:49:40 NOTICE: WARNING rclone sync try 3 failed. - /path/to/local/tree/ 2021/05/12 00:49:40 ERROR : Bisync aborted. Must run --resync to recover. ``` ### Denied downloads of "infected" or "abusive" files Google Drive has a filter for certain file types (`.exe`, `.apk`, et cetera) that by default cannot be copied from Google Drive to the local filesystem. If you are having problems, run with `--verbose` to see specifically which files are generating complaints. If the error is `This file has been identified as malware or spam and cannot be downloaded`, consider using the flag [--drive-acknowledge-abuse](/drive/#drive-acknowledge-abuse). ### Google Docs (and other files of unknown size) {#gdocs} As of `v1.65`, [Google Docs](/drive/#import-export-of-google-documents) (including Google Sheets, Slides, etc.) are now supported in bisync, subject to the same options, defaults, and limitations as in `rclone sync`. When bisyncing drive with non-drive backends, the drive -> non-drive direction is controlled by [`--drive-export-formats`](/drive/#drive-export-formats) (default `"docx,xlsx,pptx,svg"`) and the non-drive -> drive direction is controlled by [`--drive-import-formats`](/drive/#drive-import-formats) (default none.) For example, with the default export/import formats, a Google Sheet on the drive side will be synced to an `.xlsx` file on the non-drive side. In the reverse direction, `.xlsx` files with filenames that match an existing Google Sheet will be synced to that Google Sheet, while `.xlsx` files that do NOT match an existing Google Sheet will be copied to drive as normal `.xlsx` files (without conversion to Sheets, although the Google Drive web browser UI may still give you the option to open it as one.) If `--drive-import-formats` is set (it's not, by default), then all of the specified formats will be converted to Google Docs, if there is no existing Google Doc with a matching name. Caution: such conversion can be quite lossy, and in most cases it's probably not what you want! To bisync Google Docs as URL shortcut links (in a manner similar to "Drive for Desktop"), use: `--drive-export-formats url` (or [alternatives](https://rclone.org/drive/#exportformats:~:text=available%20Google%20Documents.-,Extension,macOS,-Standard%20options).) Note that these link files cannot be edited on the non-drive side -- you will get errors if you try to sync an edited link file back to drive. They CAN be deleted (it will result in deleting the corresponding Google Doc.) If you create a `.url` file on the non-drive side that does not match an existing Google Doc, bisyncing it will just result in copying the literal `.url` file over to drive (no Google Doc will be created.) So, as a general rule of thumb, think of them as read-only placeholders on the non-drive side, and make all your changes on the drive side. Likewise, even with other export-formats, it is best to only move/rename Google Docs on the drive side. This is because otherwise, bisync will interpret this as a file deleted and another created, and accordingly, it will delete the Google Doc and create a new file at the new path. (Whether or not that new file is a Google Doc depends on `--drive-import-formats`.) Lastly, take note that all Google Docs on the drive side have a size of `-1` and no checksum. Therefore, they cannot be reliably synced with the `--checksum` or `--size-only` flags. (To be exact: they will still get created/deleted, and bisync's delta engine will notice changes and queue them for syncing, but the underlying sync function will consider them identical and skip them.) To work around this, use the default (modtime and size) instead of `--checksum` or `--size-only`. To ignore Google Docs entirely, use [`--drive-skip-gdocs`](/drive/#drive-skip-gdocs). (Note that all flags starting with `--drive` are backend-specific, and therefore will cause the behavior explained in [Overridden Configs](/#overridden-configs).) ## Usage examples ### Cron {#cron} Rclone does not yet have a built-in capability to monitor the local file system for changes and must be blindly run periodically. On Windows this can be done using a _Task Scheduler_, on Linux you can use _Cron_ which is described below. The 1st example runs a sync every 5 minutes between a local directory and an OwnCloud server, with output logged to a runlog file: ``` # Minute (0-59) # Hour (0-23) # Day of Month (1-31) # Month (1-12 or Jan-Dec) # Day of Week (0-6 or Sun-Sat) # Command */5 * * * * /path/to/rclone bisync /local/files MyCloud: --check-access --filters-file /path/to/bysync-filters.txt --log-file /path/to//bisync.log ``` See [crontab syntax](https://www.man7.org/linux/man-pages/man1/crontab.1p.html#INPUT_FILES) for the details of crontab time interval expressions. If you run `rclone bisync` as a cron job, redirect stdout/stderr to a file. The 2nd example runs a sync to Dropbox every hour and logs all stdout (via the `>>`) and stderr (via `2>&1`) to a log file. ``` 0 * * * * /path/to/rclone bisync /path/to/local/dropbox Dropbox: --check-access --filters-file /home/user/filters.txt >> /path/to/logs/dropbox-run.log 2>&1 ``` ### Sharing an encrypted folder tree between hosts bisync can keep a local folder in sync with a cloud service, but what if you have some highly sensitive files to be synched? Usage of a cloud service is for exchanging both routine and sensitive personal files between one's home network, one's personal notebook when on the road, and with one's work computer. The routine data is not sensitive. For the sensitive data, configure an rclone [crypt remote](/crypt/) to point to a subdirectory within the local disk tree that is bisync'd to Dropbox, and then set up an bisync for this local crypt directory to a directory outside of the main sync tree. ### Linux server setup - `/path/to/DBoxroot` is the root of my local sync tree. There are numerous subdirectories. - `/path/to/DBoxroot/crypt` is the root subdirectory for files that are encrypted. This local directory target is setup as an rclone crypt remote named `Dropcrypt:`. See [rclone.conf](#rclone-conf-snippet) snippet below. - `/path/to/my/unencrypted/files` is the root of my sensitive files - not encrypted, not within the tree synched to Dropbox. - To sync my local unencrypted files with the encrypted Dropbox versions I manually run `bisync /path/to/my/unencrypted/files DropCrypt:`. This step could be bundled into a script to run before and after the full Dropbox tree sync in the last step, thus actively keeping the sensitive files in sync. - `bisync /path/to/DBoxroot Dropbox:` runs periodically via cron, keeping my full local sync tree in sync with Dropbox. ### Windows notebook setup - The Dropbox client runs keeping the local tree `C:\Users\MyLogin\Dropbox` always in sync with Dropbox. I could have used `rclone bisync` instead. - A separate directory tree at `C:\Users\MyLogin\Documents\DropLocal` hosts the tree of unencrypted files/folders. - To sync my local unencrypted files with the encrypted Dropbox versions I manually run the following command: `rclone bisync C:\Users\MyLogin\Documents\DropLocal Dropcrypt:`. - The Dropbox client then syncs the changes with Dropbox. ### rclone.conf snippet {#rclone-conf-snippet} ``` [Dropbox] type = dropbox ... [Dropcrypt] type = crypt remote = /path/to/DBoxroot/crypt # on the Linux server remote = C:\Users\MyLogin\Dropbox\crypt # on the Windows notebook filename_encryption = standard directory_name_encryption = true password = ... ... ``` ## Testing {#testing} You should read this section only if you are developing for rclone. You need to have rclone source code locally to work with bisync tests. Bisync has a dedicated test framework implemented in the `bisync_test.go` file located in the rclone source tree. The test suite is based on the `go test` command. Series of tests are stored in subdirectories below the `cmd/bisync/testdata` directory. Individual tests can be invoked by their directory name, e.g. `go test . -case basic -remote local -remote2 gdrive: -v` Tests will make a temporary folder on remote and purge it afterwards. If during test run there are intermittent errors and rclone retries, these errors will be captured and flagged as invalid MISCOMPAREs. Rerunning the test will let it pass. Consider such failures as noise. ### Test command syntax ``` usage: go test ./cmd/bisync [options...] Options: -case NAME Name(s) of the test case(s) to run. Multiple names should be separated by commas. You can remove the `test_` prefix and replace `_` by `-` in test name for convenience. If not `all`, the name(s) should map to a directory under `./cmd/bisync/testdata`. Use `all` to run all tests (default: all) -remote PATH1 `local` or name of cloud service with `:` (default: local) -remote2 PATH2 `local` or name of cloud service with `:` (default: local) -no-compare Disable comparing test results with the golden directory (default: compare) -no-cleanup Disable cleanup of Path1 and Path2 testdirs. Useful for troubleshooting. (default: cleanup) -golden Store results in the golden directory (default: false) This flag can be used with multiple tests. -debug Print debug messages -stop-at NUM Stop test after given step number. (default: run to the end) Implies `-no-compare` and `-no-cleanup`, if the test really ends prematurely. Only meaningful for a single test case. -refresh-times Force refreshing the target modtime, useful for Dropbox (default: false) -verbose Run tests verbosely ``` Note: unlike rclone flags which must be prefixed by double dash (`--`), the test command flags can be equally prefixed by a single `-` or double dash. ### Running tests - `go test . -case basic -remote local -remote2 local` runs the `test_basic` test case using only the local filesystem, synching one local directory with another local directory. Test script output is to the console, while commands within scenario.txt have their output sent to the `.../workdir/test.log` file, which is finally compared to the golden copy. - The first argument after `go test` should be a relative name of the directory containing bisync source code. If you run tests right from there, the argument will be `.` (current directory) as in most examples below. If you run bisync tests from the rclone source directory, the command should be `go test ./cmd/bisync ...`. - The test engine will mangle rclone output to ensure comparability with golden listings and logs. - Test scenarios are located in `./cmd/bisync/testdata`. The test `-case` argument should match the full name of a subdirectory under that directory. Every test subdirectory name on disk must start with `test_`, this prefix can be omitted on command line for brevity. Also, underscores in the name can be replaced by dashes for convenience. - `go test . -remote local -remote2 local -case all` runs all tests. - Path1 and Path2 may either be the keyword `local` or may be names of configured cloud services. `go test . -remote gdrive: -remote2 dropbox: -case basic` will run the test between these two services, without transferring any files to the local filesystem. - Test run stdout and stderr console output may be directed to a file, e.g. `go test . -remote gdrive: -remote2 local -case all > runlog.txt 2>&1` ### Test execution flow 1. The base setup in the `initial` directory of the testcase is applied on the Path1 and Path2 filesystems (via rclone copy the initial directory to Path1, then rclone sync Path1 to Path2). 2. The commands in the scenario.txt file are applied, with output directed to the `test.log` file in the test working directory. Typically, the first actual command in the `scenario.txt` file is to do a `--resync`, which establishes the baseline `{...}.path1.lst` and `{...}.path2.lst` files in the test working directory (`.../workdir/` relative to the temporary test directory). Various commands and listing snapshots are done within the test. 3. Finally, the contents of the test working directory are compared to the contents of the testcase's golden directory. ### Notes about testing - Test cases are in individual directories beneath `./cmd/bisync/testdata`. A command line reference to a test is understood to reference a directory beneath `testdata`. For example, `go test ./cmd/bisync -case dry-run -remote gdrive: -remote2 local` refers to the test case in `./cmd/bisync/testdata/test_dry_run`. - The test working directory is located at `.../workdir` relative to a temporary test directory, usually under `/tmp` on Linux. - The local test sync tree is created at a temporary directory named like `bisync.XXX` under system temporary directory. - The remote test sync tree is located at a temporary directory under `/bisync.XXX/`. - `path1` and/or `path2` subdirectories are created in a temporary directory under the respective local or cloud test remote. - By default, the Path1 and Path2 test dirs and workdir will be deleted after each test run. The `-no-cleanup` flag disables purging these directories when validating and debugging a given test. These directories will be flushed before running another test, independent of the `-no-cleanup` usage. - You will likely want to add `- /testdir/` to your normal bisync `--filters-file` so that normal syncs do not attempt to sync the test temporary directories, which may have `RCLONE_TEST` miscompares in some testcases which would otherwise trip the `--check-access` system. The `--check-access` mechanism is hard-coded to ignore `RCLONE_TEST` files beneath `bisync/testdata`, so the test cases may reside on the synched tree even if there are check file mismatches in the test tree. - Some Dropbox tests can fail, notably printing the following message: `src and dst identical but can't set mod time without deleting and re-uploading` This is expected and happens due to the way Dropbox handles modification times. You should use the `-refresh-times` test flag to make up for this. - If Dropbox tests hit request limit for you and print error message `too_many_requests/...: Too many requests or write operations.` then follow the [Dropbox App ID instructions](/dropbox/#get-your-own-dropbox-app-id). ### Updating golden results Sometimes even a slight change in the bisync source can cause little changes spread around many log files. Updating them manually would be a nightmare. The `-golden` flag will store the `test.log` and `*.lst` listings from each test case into respective golden directories. Golden results will automatically contain generic strings instead of local or cloud paths which means that they should match when run with a different cloud service. Your normal workflow might be as follows: 1. Git-clone the rclone sources locally 2. Modify bisync source and check that it builds 3. Run the whole test suite `go test ./cmd/bisync -remote local` 4. If some tests show log difference, recheck them individually, e.g.: `go test ./cmd/bisync -remote local -case basic` 5. If you are convinced with the difference, goldenize all tests at once: `go test ./cmd/bisync -remote local -golden` 6. Use word diff: `git diff --word-diff ./cmd/bisync/testdata/`. Please note that normal line-level diff is generally useless here. 7. Check the difference _carefully_! 8. Commit the change (`git commit`) _only_ if you are sure. If unsure, save your code changes then wipe the log diffs from git: `git reset [--hard]`. ### Structure of test scenarios - `/initial/` contains a tree of files that will be set as the initial condition on both Path1 and Path2 testdirs. - `/modfiles/` contains files that will be used to modify the Path1 and/or Path2 filesystems. - `/golden/` contains the expected content of the test working directory (`workdir`) at the completion of the testcase. - `/scenario.txt` contains the body of the test, in the form of various commands to modify files, run bisync, and snapshot listings. Output from these commands is captured to `.../workdir/test.log` for comparison to the golden files. ### Supported test commands - `test ` Print the line to the console and to the `test.log`: `test sync is working correctly with options x, y, z` - `copy-listings ` Save a copy of all `.lst` listings in the test working directory with the specified prefix: `save-listings exclude-pass-run` - `move-listings ` Similar to `copy-listings` but removes the source - `purge-children ` This will delete all child files and purge all child subdirs under given directory but keep the parent intact. This behavior is important for tests with Google Drive because removing and re-creating the parent would change its ID. - `delete-file ` Delete a single file. - `delete-glob ` Delete a group of files located one level deep in the given directory with names matching a given glob pattern. - `touch-glob YYYY-MM-DD ` Change modification time on a group of files. - `touch-copy YYYY-MM-DD ` Change file modification time then copy it to destination. - `copy-file ` Copy a single file to given directory. - `copy-as ` Similar to above but destination must include both directory and the new file name at destination. - `copy-dir ` and `sync-dir ` Copy/sync a directory. Equivalent of `rclone copy` and `rclone sync`. - `list-dirs ` Equivalent to `rclone lsf -R --dirs-only ` - `bisync [options]` Runs bisync against `-remote` and `-remote2`. ### Supported substitution terms - `{testdir/}` - the root dir of the testcase - `{datadir/}` - the `modfiles` dir under the testcase root - `{workdir/}` - the temporary test working directory - `{path1/}` - the root of the Path1 test directory tree - `{path2/}` - the root of the Path2 test directory tree - `{session}` - base name of the test listings - `{/}` - OS-specific path separator - `{spc}`, `{tab}`, `{eol}` - whitespace - `{chr:HH}` - raw byte with given hexadecimal code Substitution results of the terms named like `{dir/}` will end with `/` (or backslash on Windows), so it is not necessary to include slash in the usage, for example `delete-file {path1/}file1.txt`. ## Benchmarks _This section is work in progress._ Here are a few data points for scale, execution times, and memory usage. The first set of data was taken between a local disk to Dropbox. The [speedtest.net](https://speedtest.net) download speed was ~170 Mbps, and upload speed was ~10 Mbps. 500 files (~9.5 MB each) had been already synched. 50 files were added in a new directory, each ~9.5 MB, ~475 MB total. Change | Operations and times | Overall run time --------------------------------------|--------------------------------------------------------|------------------ 500 files synched (nothing to move) | 1x listings for Path1 & Path2 | 1.5 sec 500 files synched with --check-access | 1x listings for Path1 & Path2 | 1.5 sec 50 new files on remote | Queued 50 copies down: 27 sec | 29 sec Moved local dir | Queued 50 copies up: 410 sec, 50 deletes up: 9 sec | 421 sec Moved remote dir | Queued 50 copies down: 31 sec, 50 deletes down: <1 sec | 33 sec Delete local dir | Queued 50 deletes up: 9 sec | 13 sec This next data is from a user's application. They had ~400GB of data over 1.96 million files being sync'ed between a Windows local disk and some remote cloud. The file full path length was on average 35 characters (which factors into load time and RAM required). - Loading the prior listing into memory (1.96 million files, listing file size 140 MB) took ~30 sec and occupied about 1 GB of RAM. - Getting a fresh listing of the local file system (producing the 140 MB output file) took about XXX sec. - Getting a fresh listing of the remote file system (producing the 140 MB output file) took about XXX sec. The network download speed was measured at XXX Mb/s. - Once the prior and current Path1 and Path2 listings were loaded (a total of four to be loaded, two at a time), determining the deltas was pretty quick (a few seconds for this test case), and the transfer time for any files to be copied was dominated by the network bandwidth. ## References rclone's bisync implementation was derived from the [rclonesync-V2](https://github.com/cjnaz/rclonesync-V2) project, including documentation and test mechanisms, with [@cjnaz](https://github.com/cjnaz)'s full support and encouragement. `rclone bisync` is similar in nature to a range of other projects: - [unison](https://github.com/bcpierce00/unison) - [syncthing](https://github.com/syncthing/syncthing) - [cjnaz/rclonesync](https://github.com/cjnaz/rclonesync-V2) - [ConorWilliams/rsinc](https://github.com/ConorWilliams/rsinc) - [jwink3101/syncrclone](https://github.com/Jwink3101/syncrclone) - [DavideRossi/upback](https://github.com/DavideRossi/upback) Bisync adopts the differential synchronization technique, which is based on keeping history of changes performed by both synchronizing sides. See the _Dual Shadow Method_ section in [Neil Fraser's article](https://neil.fraser.name/writing/sync/). Also note a number of academic publications by [Benjamin Pierce](http://www.cis.upenn.edu/%7Ebcpierce/papers/index.shtml#File%20Synchronization) about _Unison_ and synchronization in general. ## Changelog ### `v1.65` * Copies and deletes are now handled in one operation instead of two * `--track-renames` and `--backup-dir` are now supported * Partial uploads known issue on `local`/`ftp`/`sftp` has been resolved (unless using `--inplace`) * Final listings are now generated from sync results, to avoid needing to re-list * Bisync is now much more resilient to changes that happen during a bisync run, and far less prone to critical errors / undetected changes * Bisync is now capable of rolling a file listing back in cases of uncertainty, essentially marking the file as needing to be rechecked next time. * A few basic terminal colors are now supported, controllable with [`--color`](/docs/#color-when) (`AUTO`|`NEVER`|`ALWAYS`) * Initial listing snapshots of Path1 and Path2 are now generated concurrently, using the same "march" infrastructure as `check` and `sync`, for performance improvements and less [risk of error](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=4.%20Listings%20should%20alternate%20between%20paths%20to%20minimize%20errors). * Fixed handling of unicode normalization and case insensitivity, support for [`--fix-case`](/docs/#fix-case), [`--ignore-case-sync`](/docs/#ignore-case-sync), [`--no-unicode-normalization`](/docs/#no-unicode-normalization) * `--resync` is now much more efficient (especially for users of `--create-empty-src-dirs`) * Google Docs (and other files of unknown size) are now supported (with the same options as in `sync`) ### `v1.64` * Fixed an [issue](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=1.%20Dry%20runs%20are%20not%20completely%20dry) causing dry runs to inadvertently commit filter changes * Fixed an [issue](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=2.%20%2D%2Dresync%20deletes%20data%2C%20contrary%20to%20docs) causing `--resync` to erroneously delete empty folders and duplicate files unique to Path2 * `--check-access` is now enforced during `--resync`, preventing data loss in [certain user error scenarios](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=%2D%2Dcheck%2Daccess%20doesn%27t%20always%20fail%20when%20it%20should) * Fixed an [issue](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=5.%20Bisync%20reads%20files%20in%20excluded%20directories%20during%20delete%20operations) causing bisync to consider more files than necessary due to overbroad filters during delete operations * [Improved detection of false positive change conflicts](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=1.%20Identical%20files%20should%20be%20left%20alone%2C%20even%20if%20new/newer/changed%20on%20both%20sides) (identical files are now left alone instead of renamed) * Added [support for `--create-empty-src-dirs`](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=3.%20Bisync%20should%20create/delete%20empty%20directories%20as%20sync%20does%2C%20when%20%2D%2Dcreate%2Dempty%2Dsrc%2Ddirs%20is%20passed) * Added experimental `--resilient` mode to allow [recovery from self-correctable errors](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=2.%20Bisync%20should%20be%20more%20resilient%20to%20self%2Dcorrectable%20errors) * Added [new `--ignore-listing-checksum` flag](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=6.%20%2D%2Dignore%2Dchecksum%20should%20be%20split%20into%20two%20flags%20for%20separate%20purposes) to distinguish from `--ignore-checksum` * [Performance improvements](https://forum.rclone.org/t/bisync-bugs-and-feature-requests/37636#:~:text=6.%20Deletes%20take%20several%20times%20longer%20than%20copies) for large remotes * Documentation and testing improvements