Backup methods

[Albert Shih]

Le 10/05/2018 à 02:44:18-0300, Anatoli a écrit

Hi,

>
> The replication is reasonable only if you have more than one server in your
> deployment (and both servers with the same level of security, if not you risk
> to compromise the user data) or "spool size/available disk space" is low,
> otherwise you'd need to dedicate 2 times more space than needed to store user
> data, only to take a periodic backup (+ the space needed to store the backup
> itself).

Not very sure to understand that. It's always true isn't ? If you have XTo
of data and you want n backups you will need X*(n+1) To ?

I don't see how you can avoid that, of course you can activate heavy
compression on the backup but beside of that....

> I suggest you take a look at this issue: https://github.com/cyrusimap/
> cyrus-imapd/issues/1763, where backups for small deployments were already

Thanks for the link I will read that.

> Answering the OP's question, I'm using Cyrus for 4 years now and I don't know
> about any reliable and reasonable strategy for backups of Cyrus data in SME
> environments. Summing it up:
>
>   • FS snapshots without stopping the server: a possibility of a corrupted
>     backup.
>   • FS snapshots after stopping the server: service downtime, breaking open
>     connections, delivery issues for incoming MTAs, etc. - reasonable for daily

Well that's is easy to avoid, you just have to stop postfix before stopping
the VM, when postfix is stop all incoming messages will stay on the parent
smtp server, so no loosing incoming mail.

>     backups in a 8/5 office, unreasonable for 24/7 deployments (e.g. users
>     distributed in different time zones) or for intra-day backups.

I check, stopping postfix, stopping the VM, take a snapshot, starting the
VM, take about 10-15 secondes. So I agree with you it's not a very good
solution because user still can loose the connection, but I think without
replication it's acceptable.

>   • Replication: unreasonable requirements for disk space, setup overkill.

For the setup the overkill is for me a small price vs loosing data....and
as for the disk space that's not a issue at all for me. Currently I run
dovecot and have 2 backups, so when I say to my boss « we got X To of mail »
I already got 3 * X To of disk. Say in other way, if I can afford X To, I
will say I can give you X/3 To of mail.

Regards.

--
Albert SHIH
DIO bâtiment 15
Observatoire de Paris
xmpp: jas at obspm.fr
Heure local/Local time:
Thu May 10 09:03:31 CEST 2018