162 lines
7 KiB
Markdown
162 lines
7 KiB
Markdown
---
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title: "Overview of cloud storage systems"
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description: "Overview of cloud storage systems"
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type: page
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date: "2015-09-06"
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---
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# Overview of cloud storage systems #
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Each cloud storage system is slighly different. Rclone attempts to
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provide a unified interface to them, but some underlying differences
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show through.
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## Features ##
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Here is an overview of the major features of each cloud storage system.
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| Name | Hash | ModTime | Case Insensitive | Duplicate Files | MIME Type |
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| ---------------------- |:-------:|:-------:|:----------------:|:---------------:|:---------:|
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| Google Drive | MD5 | Yes | No | Yes | R/W |
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| Amazon S3 | MD5 | Yes | No | No | R/W |
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| Openstack Swift | MD5 | Yes | No | No | R/W |
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| Dropbox | - | No | Yes | No | R |
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| Google Cloud Storage | MD5 | Yes | No | No | R/W |
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| Amazon Drive | MD5 | No | Yes | No | R |
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| Microsoft One Drive | SHA1 | Yes | Yes | No | R |
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| Hubic | MD5 | Yes | No | No | R/W |
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| Backblaze B2 | SHA1 | Yes | No | No | R/W |
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| Yandex Disk | MD5 | Yes | No | No | R/W |
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| SFTP | - | Yes | Depends | No | - |
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| The local filesystem | All | Yes | Depends | No | - |
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### Hash ###
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The cloud storage system supports various hash types of the objects.
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The hashes are used when transferring data as an integrity check and
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can be specifically used with the `--checksum` flag in syncs and in
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the `check` command.
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To use the checksum checks between filesystems they must support a
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common hash type.
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### ModTime ###
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The cloud storage system supports setting modification times on
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objects. If it does then this enables a using the modification times
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as part of the sync. If not then only the size will be checked by
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default, though the MD5SUM can be checked with the `--checksum` flag.
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All cloud storage systems support some kind of date on the object and
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these will be set when transferring from the cloud storage system.
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### Case Insensitive ###
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If a cloud storage systems is case sensitive then it is possible to
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have two files which differ only in case, eg `file.txt` and
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`FILE.txt`. If a cloud storage system is case insensitive then that
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isn't possible.
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This can cause problems when syncing between a case insensitive
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system and a case sensitive system. The symptom of this is that no
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matter how many times you run the sync it never completes fully.
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The local filesystem and SFTP may or may not be case sensitive
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depending on OS.
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* Windows - usually case insensitive, though case is preserved
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* OSX - usually case insensitive, though it is possible to format case sensitive
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* Linux - usually case sensitive, but there are case insensitive file systems (eg FAT formatted USB keys)
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Most of the time this doesn't cause any problems as people tend to
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avoid files whose name differs only by case even on case sensitive
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systems.
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### Duplicate files ###
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If a cloud storage system allows duplicate files then it can have two
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objects with the same name.
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This confuses rclone greatly when syncing - use the `rclone dedupe`
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command to rename or remove duplicates.
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### MIME Type ###
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MIME types (also known as media types) classify types of documents
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using a simple text classification, eg `text/html` or
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`application/pdf`.
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Some cloud storage systems support reading (`R`) the MIME type of
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objects and some support writing (`W`) the MIME type of objects.
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The MIME type can be important if you are serving files directly to
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HTTP from the storage system.
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If you are copying from a remote which supports reading (`R`) to a
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remote which supports writing (`W`) then rclone will preserve the MIME
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types. Otherwise they will be guessed from the extension, or the
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remote itself may assign the MIME type.
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## Optional Features ##
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All the remotes support a basic set of features, but there are some
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optional features supported by some remotes used to make some
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operations more efficient.
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| Name | Purge | Copy | Move | DirMove | CleanUp |
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| ---------------------- |:-----:|:----:|:----:|:-------:|:-------:|
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| Google Drive | Yes | Yes | Yes | Yes | No [#575](https://github.com/ncw/rclone/issues/575) |
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| Amazon S3 | No | Yes | No | No | No |
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| Openstack Swift | Yes † | Yes | No | No | No |
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| Dropbox | Yes | Yes | Yes | Yes | No [#575](https://github.com/ncw/rclone/issues/575) |
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| Google Cloud Storage | Yes | Yes | No | No | No |
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| Amazon Drive | Yes | No | Yes | Yes | No [#575](https://github.com/ncw/rclone/issues/575) |
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| Microsoft One Drive | Yes | Yes | No [#197](https://github.com/ncw/rclone/issues/197) | No [#197](https://github.com/ncw/rclone/issues/197) | No [#575](https://github.com/ncw/rclone/issues/575) |
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| Hubic | Yes † | Yes | No | No | No |
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| Backblaze B2 | No | No | No | No | Yes |
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| Yandex Disk | Yes | No | No | No | No [#575](https://github.com/ncw/rclone/issues/575) |
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| SFTP | No | No | Yes | Yes | No |
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| The local filesystem | Yes | No | Yes | Yes | No |
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### Purge ###
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This deletes a directory quicker than just deleting all the files in
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the directory.
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† Note Swift and Hubic implement this in order to delete directory
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markers but they don't actually have a quicker way of deleting files
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other than deleting them individually.
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### Copy ###
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Used when copying an object to and from the same remote. This known
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as a server side copy so you can copy a file without downloading it
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and uploading it again. It is used if you use `rclone copy` or
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`rclone move` if the remote doesn't support `Move` directly.
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If the server doesn't support `Copy` directly then for copy operations
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the file is downloaded then re-uploaded.
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### Move ###
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Used when moving/renaming an object on the same remote. This is known
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as a server side move of a file. This is used in `rclone move` if the
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server doesn't support `DirMove`.
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If the server isn't capable of `Move` then rclone simulates it with
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`Copy` then delete. If the server doesn't support `Copy` then rclone
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will download the file and re-upload it.
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### DirMove ###
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This is used to implement `rclone move` to move a directory if
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possible. If it isn't then it will use `Move` on each file (which
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falls back to `Copy` then download and upload - see `Move` section).
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### CleanUp ###
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This is used for emptying the trash for a remote by `rclone cleanup`.
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If the server can't do `CleanUp` then `rclone cleanup` will return an
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error.
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