[Borgbackup] Moving from old to new backup server

[Thorsten Schöning]

Guten Tag Oliver Hoffmann,
am Freitag, 17. September 2021 um 18:14 schrieben Sie:

> Otherwise I could set up an "empty" borg-VM and move all the clients to
> the new one. After a couple of weeks when the backups are old and
> obsolete, I could switch off the old borg server.

BorgMatic might have an interesting different idea as well: Keep the
setup as-is and start to backup into multiple repos, some hosted on
your new server. If your old system really can't be used anymore or
the backups on the new system are simply enough, just switch your VM.

https://torsion.org/borgmatic/docs/how-to/make-backups-redundant/

This would prevent RSYNC-times, creating a new VM and your restore
etc. could be kept as-is as long as storage is available on the old
server. OTOH, backup times increase from my understanding.

> I like the other idea more though. What do you think?

The main point might be if RSYNC is able to catch up with changes,
like when pruning archives. From my understanding, compacting results
in new additional files, which might make RSYNC transfer files today
which are ocmpacted and removed tomorrow in favour of additionally to
transfer files. If that happens more often than RSYNC is able to
transfer data, your migration might never finish at all in theory. :-)

Though, I guess that's pretty unlikely. If I was you, I would decide
based on how wortht he old backups in the new systems are and how long
backing up to two destinations might take. Because it might be of
benefit to really start over with new repos with new default settings
and stuff.

Otherwise, your RSYNC-approach reads fine to me and I would most
likely do the same.

> Oh, another question. What would be the best file system? Just ext4 or
> better something fancier like btfs or xfs? zfs would be nonsense as the
> raid is handled by hardware.

ZFS is not just about RAID, just as BTRFS is not only about non-RAID.
In fact, ZFS seems abit more mature, e.g. cares about things like file
name encoding instead of simply storing bytes and stuff like that. In
my opinion, it has the better interface and some better concepts like
pools vs. datasets vs. snapshots vs. clones etc. as well. There might
even be better tooling like zfs-auto-snaps, ZREP and stuff like that.
Depending on where you run your hardware, built-in encryption might be
a good argument as well, it is for me.

Said that, have a look at your distribution first and which file
system it prefers and is best integrated with. Think of updates and
problems during those, some distributions integrate tightly with
BTRFS, like SUSE, some chose ZFS instead, like Ubuntu, and provide a
lot of default tools and setup for either of both. Not only because of
updates, but backup as well.

For me, it's always BTRFS or ZFS these days, depending on the used OS,
with ZFS being in favor. XFS is in the process of catching up only and
lacks a lot of tooling and features, ext4 lacks essential concepts
like snapshots, compression etc. and seems pretty legacy to me. No
reason to start new systems with the last two mentioned in my opinion.

Mit freundlichen Grüßen

Thorsten Schöning

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