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216 lines
8.6 KiB
ReStructuredText
216 lines
8.6 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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Removing backup snapshots
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#########################
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All backup space is finite, so restic allows removing old snapshots.
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This can be done either manually (by specifying a snapshot ID to remove)
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or by using a policy that describes which snapshots to forget. For all
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remove operations, two commands need to be called in sequence:
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``forget`` to remove a snapshot and ``prune`` to actually remove the
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data that was referenced by the snapshot from the repository. This can
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be automated with the ``--prune`` option of the ``forget`` command,
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which runs ``prune`` automatically if snapshots have been removed.
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It is advisable to run ``restic check`` after pruning, to make sure
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you are alerted, should the internal data structures of the repository
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be damaged.
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Remove a single snapshot
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************************
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The command ``snapshots`` can be used to list all snapshots in a
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repository like this:
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.. code-block:: console
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$ restic -r /tmp/backup snapshots
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enter password for repository:
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ID Date Host Tags Directory
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----------------------------------------------------------------------
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40dc1520 2015-05-08 21:38:30 kasimir /home/user/work
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79766175 2015-05-08 21:40:19 kasimir /home/user/work
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bdbd3439 2015-05-08 21:45:17 luigi /home/art
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590c8fc8 2015-05-08 21:47:38 kazik /srv
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9f0bc19e 2015-05-08 21:46:11 luigi /srv
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In order to remove the snapshot of ``/home/art``, use the ``forget``
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command and specify the snapshot ID on the command line:
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.. code-block:: console
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$ restic -r /tmp/backup forget bdbd3439
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enter password for repository:
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removed snapshot d3f01f63
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Afterwards this snapshot is removed:
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.. code-block:: console
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$ restic -r /tmp/backup snapshots
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enter password for repository:
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ID Date Host Tags Directory
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----------------------------------------------------------------------
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40dc1520 2015-05-08 21:38:30 kasimir /home/user/work
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79766175 2015-05-08 21:40:19 kasimir /home/user/work
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590c8fc8 2015-05-08 21:47:38 kazik /srv
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9f0bc19e 2015-05-08 21:46:11 luigi /srv
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But the data that was referenced by files in this snapshot is still
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stored in the repository. To cleanup unreferenced data, the ``prune``
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command must be run:
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.. code-block:: console
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$ restic -r /tmp/backup prune
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enter password for repository:
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counting files in repo
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building new index for repo
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[0:00] 100.00% 22 / 22 files
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repository contains 22 packs (8512 blobs) with 100.092 MiB bytes
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processed 8512 blobs: 0 duplicate blobs, 0B duplicate
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load all snapshots
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find data that is still in use for 1 snapshots
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[0:00] 100.00% 1 / 1 snapshots
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found 8433 of 8512 data blobs still in use
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will rewrite 3 packs
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creating new index
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[0:00] 86.36% 19 / 22 files
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saved new index as 544a5084
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done
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Afterwards the repository is smaller.
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You can automate this two-step process by using the ``--prune`` switch
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to ``forget``:
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.. code-block:: console
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$ restic forget --keep-last 1 --prune
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snapshots for host mopped, directories /home/user/work:
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keep 1 snapshots:
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ID Date Host Tags Directory
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----------------------------------------------------------------------
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4bba301e 2017-02-21 10:49:18 mopped /home/user/work
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remove 1 snapshots:
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ID Date Host Tags Directory
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----------------------------------------------------------------------
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8c02b94b 2017-02-21 10:48:33 mopped /home/user/work
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1 snapshots have been removed, running prune
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counting files in repo
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building new index for repo
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[0:00] 100.00% 37 / 37 packs
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repository contains 37 packs (5521 blobs) with 151.012 MiB bytes
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processed 5521 blobs: 0 duplicate blobs, 0B duplicate
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load all snapshots
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find data that is still in use for 1 snapshots
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[0:00] 100.00% 1 / 1 snapshots
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found 5323 of 5521 data blobs still in use, removing 198 blobs
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will delete 0 packs and rewrite 27 packs, this frees 22.106 MiB
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creating new index
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[0:00] 100.00% 30 / 30 packs
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saved new index as b49f3e68
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done
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Removing snapshots according to a policy
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****************************************
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Removing snapshots manually is tedious and error-prone, therefore restic
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allows specifying which snapshots should be removed automatically
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according to a policy. You can specify how many hourly, daily, weekly,
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monthly and yearly snapshots to keep, any other snapshots are removed.
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The most important command-line parameter here is ``--dry-run`` which
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instructs restic to not remove anything but print which snapshots would
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be removed.
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When ``forget`` is run with a policy, restic loads the list of all
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snapshots, then groups these by host name and list of directories. The grouping
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options can be set with ``--group-by``, to only group snapshots by paths and
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tags use ``--group-by paths,tags``. The policy is then applied to each group of
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snapshots separately. This is a safety feature.
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The ``forget`` command accepts the following parameters:
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- ``--keep-last n`` never delete the ``n`` last (most recent) snapshots
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- ``--keep-hourly n`` for the last ``n`` hours in which a snapshot was
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made, keep only the last snapshot for each hour.
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- ``--keep-daily n`` for the last ``n`` days which have one or more
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snapshots, only keep the last one for that day.
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- ``--keep-weekly n`` for the last ``n`` weeks which have one or more
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snapshots, only keep the last one for that week.
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- ``--keep-monthly n`` for the last ``n`` months which have one or more
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snapshots, only keep the last one for that month.
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- ``--keep-yearly n`` for the last ``n`` years which have one or more
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snapshots, only keep the last one for that year.
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- ``--keep-tag`` keep all snapshots which have all tags specified by
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this option (can be specified multiple times).
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Additionally, you can restrict removing snapshots to those which have a
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particular hostname with the ``--hostname`` parameter, or tags with the
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``--tag`` option. When multiple tags are specified, only the snapshots
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which have all the tags are considered. For example, the following command
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removes all but the latest snapshot of all snapshots that have the tag ``foo``:
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.. code-block:: console
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$ restic forget --tag foo --keep-last 1
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This command removes all but the last snapshot of all snapshots that have
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either the ``foo`` or ``bar`` tag set:
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.. code-block:: console
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$ restic forget --tag foo --tag bar --keep-last 1
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To only keep the last snapshot of all snapshots with both the tag ``foo`` and
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``bar`` set use:
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.. code-block:: console
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$ restic forget --tag foo,tag bar --keep-last 1
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All the ``--keep-*`` options above only count
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hours/days/weeks/months/years which have a snapshot, so those without a
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snapshot are ignored.
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For safety reasons, restic refuses to act on an "empty" policy. For example,
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if one were to specify ``--keep-last 0`` to forget *all* snapshots in the
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repository, restic will respond that no snapshots will be removed. To delete
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all snapshots, use ``--keep-last 1`` and then finally remove the last
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snapshot ID manually (by passing the ID to ``forget``).
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All snapshots are evaluated against all matching ``--keep-*`` counts. A
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single snapshot on 2017-09-30 (Sun) will count as a daily, weekly and monthly.
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Let's explain this with an example: Suppose you have only made a backup
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on each Sunday for 12 weeks. Then ``forget --keep-daily 4`` will keep
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the last four snapshots for the last four Sundays, but remove the rest.
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Only counting the days which have a backup and ignore the ones without
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is a safety feature: it prevents restic from removing many snapshots
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when no new ones are created. If it was implemented otherwise, running
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``forget --keep-daily 4`` on a Friday would remove all snapshots!
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Another example: Suppose you make daily backups for 100 years. Then
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``forget --keep-daily 7 --keep-weekly 5 --keep-monthly 12 --keep-yearly 75``
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will keep the most recent 7 daily snapshots, then 4 (remember, 7 dailies
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already include a week!) last-day-of-the-weeks and 11 or 12
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last-day-of-the-months (11 or 12 depends if the 5 weeklies cross a month).
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And finally 75 last-day-of-the-year snapshots. All other snapshots are
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removed.
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