[Borgbackup] Determine which files greatly increased backup size

[Thomas Waldmann]

> I'm evaluating Borg Backup as a potential replacement of rdiff-backup. I
> really like its reduplication and compression, however having a daily
> backup of my Firefox profiles (around 300MB) rdiff-backup has an
> increment of ~35MB, while with Borg it is ~65MB. As it is a daily backup
> it give around 10GB more space allocated per year.
> 
> Sure, with proper data retention it would be less, but I would like to
> investigate it and maybe play with the bucket size (or exclude some
> wonky files from a backup).

You can play with --chunker-params, but be warned that having smaller
target chunk size also means having more chunks to manage, requiring
more time and space (on disk, in memory) to deal with them.

The latter is the reason why borg targets 2MiB chunks by default.

> Is it possible to get detailed information at the end of a backup
> creation how much given file increased a backup (archive) size?

No. You can use --stats and use some special placeholders for borg list,
but I guess that won't help enough.

What usually helps a bit is to keep the --stats and --list output of a
borg create run and do educated guesses based on these.


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