borg/docs/man/borg-check.1

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.TH BORG-CHECK 1 "2019-11-01" "" "borg backup tool"
.SH NAME
borg-check \- Check repository consistency
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.SH SYNOPSIS
.sp
borg [common options] check [options] [REPOSITORY_OR_ARCHIVE]
.SH DESCRIPTION
.sp
The check command verifies the consistency of a repository and the corresponding archives.
.sp
First, the underlying repository data files are checked:
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.IP \(bu 2
For all segments the segment magic (header) is checked
.IP \(bu 2
For all objects stored in the segments, all metadata (e.g. crc and size) and
all data is read. The read data is checked by size and CRC. Bit rot and other
types of accidental damage can be detected this way.
.IP \(bu 2
If we are in repair mode and a integrity error is detected for a segment,
we try to recover as many objects from the segment as possible.
.IP \(bu 2
In repair mode, it makes sure that the index is consistent with the data
stored in the segments.
.IP \(bu 2
If you use a remote repo server via ssh:, the repo check is executed on the
repo server without causing significant network traffic.
.IP \(bu 2
The repository check can be skipped using the \fB\-\-archives\-only\fP option.
.IP \(bu 2
A repository check can be time consuming. Partial checks are possible with the \fB\-\-max\-duration\fP option.
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.sp
Second, the consistency and correctness of the archive metadata is verified:
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.IP \(bu 2
Is the repo manifest present? If not, it is rebuilt from archive metadata
chunks (this requires reading and decrypting of all metadata and data).
.IP \(bu 2
Check if archive metadata chunk is present. if not, remove archive from
manifest.
.IP \(bu 2
For all files (items) in the archive, for all chunks referenced by these
files, check if chunk is present.
If a chunk is not present and we are in repair mode, replace it with a same\-size
replacement chunk of zeros.
If a previously lost chunk reappears (e.g. via a later backup) and we are in
repair mode, the all\-zero replacement chunk will be replaced by the correct chunk.
This requires reading of archive and file metadata, but not data.
.IP \(bu 2
If we are in repair mode and we checked all the archives: delete orphaned
chunks from the repo.
.IP \(bu 2
if you use a remote repo server via ssh:, the archive check is executed on
the client machine (because if encryption is enabled, the checks will require
decryption and this is always done client\-side, because key access will be
required).
.IP \(bu 2
The archive checks can be time consuming, they can be skipped using the
\fB\-\-repository\-only\fP option.
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.sp
The \fB\-\-max\-duration\fP option can be used to split a long\-running repository check into multiple partial checks.
After the given number of seconds the check is interrupted. The next partial check will continue where the
previous one stopped, until the complete repository has been checked. Example: Assuming a full check took 7
hours, then running a daily check with \-\-max\-duration=3600 (1 hour) would result in one full check per week.
.sp
Attention: Partial checks can only do way less checks than a full check (only the CRC32 checks on segment file
entries are done) and cannot be combined with \fB\-\-repair\fP\&. Partial checks may therefore be useful only with very
large repositories where a full check would take too long. Doing a full repository check aborts a partial check;
the next partial check will start from the beginning.
.sp
The \fB\-\-verify\-data\fP option will perform a full integrity verification (as opposed to
checking the CRC32 of the segment) of data, which means reading the data from the
repository, decrypting and decompressing it. This is a cryptographic verification,
which will detect (accidental) corruption. For encrypted repositories it is
tamper\-resistant as well, unless the attacker has access to the keys.
.sp
It is also very slow.
.SH OPTIONS
.sp
See \fIborg\-common(1)\fP for common options of Borg commands.
.SS arguments
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.TP
.B REPOSITORY_OR_ARCHIVE
repository or archive to check consistency of
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.SS optional arguments
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.TP
.B \-\-repository\-only
only perform repository checks
.TP
.B \-\-archives\-only
only perform archives checks
.TP
.B \-\-verify\-data
perform cryptographic archive data integrity verification (conflicts with \fB\-\-repository\-only\fP)
.TP
.B \-\-repair
attempt to repair any inconsistencies found
.TP
.B \-\-save\-space
work slower, but using less space
.TP
.BI \-\-max\-duration \ SECONDS
do only a partial repo check for max. SECONDS seconds (Default: unlimited)
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.SS Archive filters
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.TP
.BI \-P \ PREFIX\fP,\fB \ \-\-prefix \ PREFIX
only consider archive names starting with this prefix.
.TP
.BI \-a \ GLOB\fP,\fB \ \-\-glob\-archives \ GLOB
only consider archive names matching the glob. sh: rules apply, see "borg help patterns". \fB\-\-prefix\fP and \fB\-\-glob\-archives\fP are mutually exclusive.
.TP
.BI \-\-sort\-by \ KEYS
Comma\-separated list of sorting keys; valid keys are: timestamp, name, id; default is: timestamp
.TP
.BI \-\-first \ N
consider first N archives after other filters were applied
.TP
.BI \-\-last \ N
consider last N archives after other filters were applied
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.SH SEE ALSO
.sp
\fIborg\-common(1)\fP
.SH AUTHOR
The Borg Collective
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