Re: [gentoo-user] [OT] SMR drives (WAS: cryptsetup close and device in use when it is not)

[Frank Steinmetzger <Warp_7@gmx.de>]

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Am Mon, Aug 02, 2021 at 02:12:24PM +0800 schrieb William Kenworthy:
> >>> And you are storing several machines into a single repo? The docs say this
> >>> is not supported officially. But I have one repo each for /, /home and data
> >>> for both my PC and laptop. Using a wrapper script, I create snapshots that
> >>> are named $HOSTNAME_$DATE in each repo.
> >> Basicly yes: I use a once per hour snapshot of approximately 500Gib of
> >> data on moosefs, plus borgbackups 3 times a day to individual repos on
> >> moosefs for each host.
> > So you have:
> > Host A ──[hourly]──> Online-Borg A ─┐
> >                                     ├──[3/day]──> Offline-Borg
> > Host B ──[hourly]──> Online-Borg B ─┘
> > ?
> > […]
>
> Hi Frank,
>
> Not quite - I see I could have been clearer.  I "experiment" a lot -
> which means things break so I need to get back running quickly.  So the
> purpose of the online repos and snapshots is just for that - quick
> recovery.

Whenever you say snapshot, you meen moosefs snapshots, right? Up until this
thread I’ve never heard of that FS.

I would love to play more with storage systems, moving stuff around, backing
it up, assigning space and so on (basically play admin for a few people),
but apart from my ZFS-based NAS, I have nothing that would need this. I run
a nextcloud instance on my shared internet host and one on my raspi. That’s
as far as it gets. :D

> stage 1: online, immediately available
>
> Hosts (those with actual attached storage - a mixture of intel, arm32
> and arm64 devices are backed up to their own borg repo 3 times a day via
> push.  One repo per machine on moosefs.
>
> A separate script does an hourly backup of VM, LXC images, and various
> data stores via a moosefs snapshot.
>
> stage 2: resource management for the snapshots
>
> 3 times a day, a script does a borg create on the latest snapshop at the
> time

So you mount the latest snapshot or access it in some other way and borg
*its* content, not the live data, right?

> and when complete deletes all previous snapshots (-1) so at that
> point I have two older snapshots available + a couple created during the
> borg run - note that large multi GiB snapshots can quickly use up all
> memory (32GiB) on the moosefs master unless culled regularly.

Sounds a bit delicate to me. If one link fails for some reason undetectedly,
you risk clog-up.

> stage 3: offline because disasters happen :)
>
> All borg repos are on moosefs with a single root directory
> (/mnt/mfs/backups) so once every day or so I manually mount the offline
> disk and do a borg create on the backup directory.

What happens if that daily borg runs while the repos are being written to?

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