70 lines
3.1 KiB
ReStructuredText
70 lines
3.1 KiB
ReStructuredText
..
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Normally, there are no heading levels assigned to certain characters as the structure is
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determined from the succession of headings. However, this convention is used in Python’s
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Style Guide for documenting which you may follow:
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# with overline, for parts
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* for chapters
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= for sections
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- for subsections
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^ for subsubsections
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" for paragraphs
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########################
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Tuning Backup Parameters
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########################
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Restic offers a few parameters that allow tuning the backup. The default values should
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work well in general although specific use cases can benefit from different non-default
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values. As the restic commands evolve over time, the optimal value for each parameter
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can also change across restic versions.
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Backend Connections
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===================
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Restic uses a global limit for the number of concurrent connections to a backend.
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This limit can be configured using ``-o <backend-name>.connections=5``, for example for
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the REST backend the parameter would be ``-o rest.connections=5``. By default restic uses
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``5`` connections for each backend, except for the local backend which uses a limit of ``2``.
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The defaults should work well in most cases. For high-latency backends it can be beneficial
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to increase the number of connections. Please be aware that this increases the resource
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consumption of restic and that a too high connection count *will degrade performace*.
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CPU Usage
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=========
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By default, restic uses all available CPU cores. You can set the environment variable
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`GOMAXPROCS` to limit the number of used CPU cores. For example to use a single CPU core,
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use `GOMAXPROCS=1`. Limiting the number of usable CPU cores, can slightly reduce the memory
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usage of restic.
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Compression
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===========
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For a repository using at least repository format version 2, you can configure how data
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is compressed with the option ``--compression``. It can be set to ```auto``` (the default,
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which will compress very fast), ``max`` (which will trade backup speed and CPU usage for
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slightly better compression), or ``off`` (which disables compression). Each setting is
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only applied for the single run of restic. The option can also be set via the environment
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variable ``RESTIC_COMPRESSION``.
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Pack Size
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=========
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In certain instances, such as very large repositories, it is desired to have larger pack
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sizes to reduce the number of files in the repository. Notable examples are OpenStack
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Swift and some Google Drive Team accounts, where there are hard limits on the total
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number of files. This can be achieved by either using the ``--min-packsize`` flag
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or defining the ``$RESTIC_MIN_PACKSIZE`` environment variable. Restic currently defaults
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to a 16MB minimum pack size.
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The side effect of increasing the pack size is increased client memory usage. A bit of
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tuning may be required to strike a balance between memory usage and number of pack files.
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Restic uses the majority of it's memory according to the pack size, multiplied by the number
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of parallel writers. For example, if you have 4 parallel writers (restic creates one per
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available CPU), With a minimum pack size of 64 (Megabytes), you'll get a *minimum* of 256MB
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of memory usage.
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