restic/doc/047_tuning_backup_parameters.rst

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Tuning Backup Parameters
########################

Restic offers a few parameters that allow tuning the backup. The default values should
work well in general although specific use cases can benefit from different non-default
values. As the restic commands evolve over time, the optimal value for each parameter
can also change across restic versions.


Backend Connections
===================

Restic uses a global limit for the number of concurrent connections to a backend.
This limit can be configured using ``-o <backend-name>.connections=5``, for example for
the REST backend the parameter would be ``-o rest.connections=5``. By default restic uses
``5`` connections for each backend, except for the local backend which uses a limit of ``2``.
The defaults should work well in most cases. For high-latency backends it can be beneficial
to increase the number of connections. Please be aware that this increases the resource
consumption of restic and that a too high connection count *will degrade performace*.


CPU Usage
=========

By default, restic uses all available CPU cores. You can set the environment variable
`GOMAXPROCS` to limit the number of used CPU cores. For example to use a single CPU core,
use `GOMAXPROCS=1`. Limiting the number of usable CPU cores, can slightly reduce the memory
usage of restic.


Compression
===========

For a repository using a least repository format version 2, you can configure how data
is compressed with the option ``--compression``. It can be set to ```auto``` (the default,
which will compress very fast), ``max`` (which will trade backup speed and CPU usage for
slightly better compression), or ``off`` (which disables compression). Each setting is
only applied for the single run of restic.