bup-fsck(1)

NAME
bup-fsck - verify or repair a bup repository

SYNOPSIS
bup fsck [-r] [-g] [-v] [--quick] [-j jobs] [--par2-ok] [--disable-par2] [filenames...]

DESCRIPTION
bup fsck is a tool for validating bup repositories in the same way that git fsck validates git repositories.

It can also generate and/or use “recovery blocks” using the par2(1) tool (if you have it installed). This allows you to recover from damaged blocks covering up to 5% of your .pack files.

In a normal backup system, damaged blocks are less important, because there tends to be enough data duplicated between backup sets that a single damaged backup set is non-critical. In a deduplicating backup system like bup, however, no block is ever stored more than once, even if it is used in every single backup. If that block were to be unrecoverable, all your backup sets would be damaged at once. Thus, it’s important to be able to verify the integrity of your backups and recover from disk errors if they occur.

WARNING: bup fsck’s recovery features are not available unless you have the free par2(1) package installed on your bup server.

WARNING: bup fsck obviously cannot recover from a complete disk failure. If your backups are important, you need to carefully consider redundancy (such as using RAID for multi-disk redundancy, or making off-site backups for site redundancy).

OPTIONS

-r, --repair
    attempt to repair any damaged packs using existing recovery blocks. (Requires par2(1).)

-g, --generate
    generate recovery blocks for any packs that don’t already have them. (Requires par2(1).)

-v, --verbose
    increase verbosity (can be used more than once).

--quick
    don’t run a full git verify-pack on each pack file; instead just check the final checksum. This can cause a significant speedup with no obvious decrease in reliability. However, you may want to avoid this option if you’re paranoid. Has no effect on packs that already have recovery information.

-j, --jobs=numjobs
    maximum number of pack verifications to run at a time. The optimal value for this option depends how fast your CPU can verify packs vs. your disk throughput. If you run too many jobs at once, your disk will get saturated by seeking back and forth between files and performance will actually decrease, even if numjobs is less than the number of CPU cores on your system. You can experiment with this option to find the optimal value.

--par2-ok
    immediately return 0 if par2(1) is installed and working, or 1 otherwise. Do not actually check anything.

--disable-par2
    pretend that par2(1) is not installed, and ignore all recovery blocks.

EXAMPLES

        # generate recovery blocks for all packs that don't
        # have them
        bup fsck -g
        # generate recovery blocks for a particular pack
        bup fsck -g ~/.bup/objects/pack/153a1420cb1c8*.pack
        # check all packs for correctness (can be very slow!)
        bup fsck
        # check all packs for correctness and recover any
        # damaged ones
        bup fsck -r
        # check a particular pack for correctness and recover
        # it if damaged
        bup fsck -r ~/.bup/objects/pack/153a1420cb1c8*.pack
        # check if recovery blocks are available on this system
        if bup fsck --par2-ok; then
            echo "par2 is ok"
        fi

SEE ALSO
bup-damage(1), fsck(1), git-fsck(1)

BUP
Part of the bup(1) suite.

AUTHORS
Avery Pennarun apenwarr@gmail.com