ZFS storage and backup

[James]

On 14/11/2021 14:14, infoomatic wrote:
> My setups are nothing special with few users, however, I would like to
> have a nice setup, maybe some of you could contribute to this thread. We
> are using slow spinning disks, but we may consider using ssds in a
> not-so-distant future.
>
> *) storages: any infos on ZFS options or whether to use mdbox or sdbox,
> and what configs/options regarding compression etc.

OmniOS with ZFS here.

I use maildir - just a personal choice and inertia, I have no 
performance data, no problem and no reason to change.  I like being able 
to see emails as plain files.

zfs set compress=gzip

and no other changes from default, oh and atime=off on the whole 
machine.  Email gzips well, most other ZFSes I leave on lz4.  I say it 
is better to use the file system to compress rather than getting dovecot 
to do it.

$ zfs get compress,compressratio,used ...
NAME              PROPERTY       VALUE     SOURCE
...../..../vmail  compression    gzip      received
...../..../vmail  compressratio  1.82x     -
...../..../vmail  used           8.55G     -

25 mailbox users ("nothing special with few users").

I moved the storage from HDD (mirror plus log) to SSD (mirror) and no 
one noticed, not even me knowing it had been done and over a local 
network.  I have enough RAM such that repeated reads are cached.

I will use native ZFS encryption soon.  I see no performance issues in test.

Don't get hung up on ZFS tuning, mostly ZFS just works.


> *) backup: what is a best practice regarding backups? - using only the
> dovecot tools or leveraging the great features of ZFS (or both) with
> snapshots etc.?

I use automated snapshots and zfs send/receive to a remote backup 
machine.  I auto copy many ZFSes this way so it is minimal effort to do 
email too.

James