Borgbackup no longer supports lzma

General Discussion
1

See also: Fallout from the XZ issue, a question to our users

borgbackup offers several compression options for backup archives, including lz4, zstd, zlib, and lzma. Unfortunately, in removing the tainted xz from everything we can, borg on Clear Linux also loses lzma support. If you’re not using lzma in your archives, you shouldn’t have an issue; borg will continue working with any of the other three (or none). But if you do, you won’t be able to read those existing archives unless you install Python lzma support manually.

2

You should be able to check existing archives like this (in which the archive was created with zlib compression):

$ borg info /tmp/foo::test1
Archive name: test1
Archive fingerprint: 63ffb3ac33f2355d55e158ea64f7837ba2d1b566f2d558c27e7ac2aa664ffdd0
Comment:
Hostname: mycompy
Username: thisguy
Time (start): Tue, 2024-04-02 17:54:24
Time (end): Tue, 2024-04-02 17:54:24
Duration: 0.00 seconds
Number of files: 1
Command line: /usr/bin/borg create -C zlib /tmp/foo::test1 /home/thisguy
Utilization of maximum supported archive size: 0%
------------------------------------------------------------------------------
                       Original size      Compressed size    Deduplicated size
This archive:                7.92 kB              3.26 kB              3.90 kB
All archives:                7.92 kB              3.26 kB              3.90 kB

                       Unique chunks         Total chunks
Chunk index:                       3                    3
3

Will tar not be able to support --xz “lzma” as well?

4

tar forks xz -d to handle it, so you’re good as long as we keep shipping the standalone xz/lzma utilities.

5

Thank you for letting me know. I have a lot of existing archives created using the --xz flag.

6

we have no plans to remove /usr/bin/xz

we are trying to not use liblzma in places that don’t really need it – basically after last week that’s only sensible

7

I’m adding a bundle, xz-lzma-i-accept-the-risks, that will provide Python lzma support. If you add this bundle, borg operations on lzma archives should work. Without it, borg will fail on those archives. I recommend installing this only long enough to convert those archives to a different compression algorithm like lz4 or zstd.