TheArchive/restic
1
0
Fork 0
mirror of https://github.com/restic/restic.git synced 2025-08-22 17:30:06 +00:00
Code Issues Packages Projects Releases Wiki Activity

document backup --group-by

Browse Source
This commit is contained in:
Michael Eischer
2022-12-10 16:02:29 +01:00
parent 2885db7902
commit 0ce182f044
4 changed files with 30 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
doc/040_backup.rst
View File

@@ -139,13 +139,24 @@ File change detection
*********************
When restic encounters a file that has already been backed up, whether in the
current backup or a previous one, it makes sure the file's contents are only
current backup or a previous one, it makes sure the file's content is only
stored once in the repository. To do so, it normally has to scan the entire
contents of every file. Because this can be very expensive, restic also uses a
content of the file. Because this can be very expensive, restic also uses a
change detection rule based on file metadata to determine whether a file is
likely unchanged since a previous backup. If it is, the file is not scanned
again.
The previous backup snapshot, called "parent" snaphot in restic terminology,
is determined as follows. By default restic groups snapshots by hostname and
backup paths, and then selects the latest snapshot in the group that matches
the current backup. You can change the selection criteria using the
``--group-by`` option, which defaults to ``host,paths``. To select the latest
snapshot with the same paths independent of the hostname, use ``paths``. Or,
to only consider the hostname and tags, use ``host,tags``. Alternatively, it
is possible to manually specify a specific parent snapshot using the
``--parent`` option. Finally, note that one would normally set the
``--group-by`` option for the ``forget`` command to the same value.
Change detection is only performed for regular files (not special files,
symlinks or directories) that have the exact same path as they did in a
previous backup of the same location. If a file or one of its containing