[borgbackup] deduplication for backup of largely identical systems

[Thomas Waldmann]

Hi Marc,

> most of my machines are running Debian stable. It is therefore likely
> that parts of the file system such as /usr will be largely identical
> over most of my system.

Yeah (plus some other parts, too).

> To take advantage of borg's deduplication feature in this scale, it
> sounds enticing to have all backups run into the same repository (borg
> init ssh://backuphost//repository once and borg create
> ssh:/backuphost//repository::localhost-date / for the actual backups).
> 
> Is that a recommended procedure?

You can backup multiple machines to same repo, but:
- be careful with prune (use prefix option, use dry-run)
- there is an exclusive write lock, so they will run sequential, not in
parallel
- the local cache on each machine will need a resync each time another
machine has updated the repo to bring it in sync again with the repo state

> I guess that risk of repository loss
> is higher that way, only one backup can write to the repository at a
> single time, and all machines would be able to read each other's
> backups since it's the same repository with the same key.

Exactly.

> Are there any other implications that I need to be aware of before
> engaging in borg deduplicating backup in scale?

Only what we have above. (AFAIK) ^^

Cheers,

Thomas