FreeBSD Manual Pages
bup-damage(1) General Commands Manual bup-damage(1) NAME bup-damage - randomly destroy blocks of a file SYNOPSIS bup damage [-n count] [-s maxsize] [--percent pct] [-S seed] [--equal] <filenames...> DESCRIPTION Use bup damage to deliberately destroy blocks in a .pack or .idx file (from .bup/objects/pack) to test the recovery features of bup-fsck(1) or other programs. THIS PROGRAM IS EXTREMELY DANGEROUS AND WILL DESTROY YOUR DATA bup damage is primarily useful for automated or manual tests of data recovery tools, to reassure yourself that the tools actually work. OPTIONS -n, --num=numblocks the number of separate blocks to damage in each file (default 10). Note that it's possible for more than one damaged segment to fall in the same bup-fsck(1) recovery block, so you might not damage as many recovery blocks as you expect. If this is a problem, use --equal. -s, --size=maxblocksize the maximum size, in bytes, of each damaged block (default 1 un- less --percent is specified). Note that because of the way bup-fsck(1) works, a multi-byte block could fall on the boundary between two recovery blocks, and thus damaging two separate re- covery blocks. In small files, it's also possible for a damaged block to be larger than a recovery block. If these issues might be a problem, you should use the default damage size of one byte. --percent=maxblockpercent the maximum size, in percent of the original file, of each dam- aged block. If both --size and --percent are given, the maximum block size is the minimum of the two restrictions. You can use this to ensure that a given block will never damage more than one or two git-fsck(1) recovery blocks. -S, --seed=randomseed seed the random number generator with the given value. If you use this option, your tests will be repeatable, since the dam- aged block offsets, sizes, and contents will be the same every time. By default, the random numbers are different every time (so you can run tests in a loop and repeatedly test with differ- ent damage each time). --equal instead of choosing random offsets for each damaged block, space the blocks equally throughout the file, starting at offset 0. If you also choose a correct maximum block size, this can guar- antee that any given damage block never damages more than one git-fsck(1) recovery block. (This is also guaranteed if you use -s 1.) EXAMPLES # make a backup in case things go horribly wrong cp -pPR ~/.bup/objects/pack ~/bup-packs.bak # generate recovery blocks for all packs bup fsck -g # deliberately damage the packs bup damage -n 10 -s 1 -S 0 ~/.bup/objects/pack/*.{pack,idx} # recover from the damage bup fsck -r SEE ALSO bup-fsck(1), par2(1) BUP Part of the bup(1) suite. AUTHORS Avery Pennarun <apenwarr@gmail.com> Bup 0.32 2021-01-09 bup-damage(1)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | SEE ALSO | BUP | AUTHORS
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=bup-damage&sektion=1&manpath=FreeBSD+Ports+15.0>