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.
EXAMPLE
# 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>.