Rsync to backup dbox with SIS
We will be deploying a replacement Dovecot server soon, and we are planning to use maildir for the primary storage, but with an archive namespace using mdbox (or perhaps sdbox), and SIS.
Our backup servers and (luke)warm spare server need to obtain full copies of the mail store. For the maildirs I know I can simply use rsync (we already use it here).
I'm a little wary of using rsync with mdbox and SIS though.
Obviously we would have to use the -H option of rsync to avoid duplicating the hard linked data, does anybody have any experience with how this scales? I've considered simply rsyncing the /var/mail/dovecot/attach/??/??/hashes folders. Is there a tool that can reconstruct the /var/mail/dovecot/attach/??/??/*-* links for a list of messages in that case?
I'm aware of "doveadm backup", and (although it currently throws up a few errors) it seems like it might be a valid solution for our warm spare server. Our backup servers, on the other hand, aren't supposed to be visible to the production machines, with the exception of the backup machine sshing in to do an rsync each night. We can't install dovecot on them.
To perform partial email recovery in maildir, we can simply log into a backup server, grep for emails of interest, and then scp them into a maildir new/ subfolder on the mail server to recover them.
What about using dbox? I can identify /var/mail/dovecot/archive/ash/dbox/storage/m.* files, and identify necessary attachments under /var/mail/dovecot/attach/??/??/ but once I've copied them over to the mail server is there a safe way to import them? Actually, converting to a maildir style file would be adequate if there is a script anywhere to do this. We'd still rather be backing up the deduplicated mailstore for obvious reasons.
Has anybody got any suggestions?
I'm aware of "dsync backup questions" ( https://www.dovecot.org/list/dovecot/2013-February/088070.html ) but there didn't really seem to be a solution.
Thanks,
Ash
PS Our current server has 257 users (though perhaps 100 are active), using around 225G in total.
PPS Proposed new server configuration:
mail_location = maildir:~/Maildir:LAYOUT=fs mail_attachment_dir = /var/mail/dovecot/attach mail_attachment_fs = sis posix mail_attachment_hash = %{sha1} mail_attachment_min_size = 128 k
namespace _archive { list = yes location = mdbox:/var/mail/dovecot/archive/%n/dbox prefix = Archive/ separator = / subscriptions = yes type = private }
namespace _private { inbox = yes type = private separator = / subscriptions = yes prefix = }
To opt-in to receiving communications from us or to update your email preferences please go to https://lists.comtek.co.uk/prefs. To be removed from receiving all communications from the Comtek Group, please unsubscribe at https://lists.comtek.co.uk/prefs and accept our apologies for any inconvenience caused.
The Comtek Group respects your privacy. Please find our privacy policy at http://www.comtek.co.uk/privacy-policy
This email and any attachments are confidential. If you are not the named recipient, please notify the sender immediately. The unauthorised use, disclosure, copying or alteration of this message or its attachments is strictly prohibited. Opinions expressed in this message are those of the individual and not Comtek Network Systems (UK) Ltd unless indicated by an authorised representative independent of this message. Comtek Network Systems does not accept responsibility for any changes to this message after it has been sent.
Company Details: Comtek Network Systems (UK) Ltd. Registered Office: Comtek Network Systems (UK) Ltd, Unit 108, Tenth Avenue (Zone 3), Deeside Industrial Park, Deeside, Flintshire, CH5 2UA. Comtek Network Systems (UK) Ltd is a company registered in England and Wales with company number 05929974.
On 1/25/2019 1:33 PM, ash-dovecot@comtek.co.uk wrote:
We will be deploying a replacement Dovecot server soon, and we are planning to use maildir for the primary storage, but with an archive namespace using mdbox (or perhaps sdbox), and SIS.
Our backup servers and (luke)warm spare server need to obtain full copies of the mail store. For the maildirs I know I can simply use rsync (we already use it here).
I'm a little wary of using rsync with mdbox and SIS though.
Significantly limited knowledge opinions below:
Probably not the answer you want - but I would strongly suggest using Dovecot replication. Dovecot replication Just Works - so don't reinvent the wheel when Timo provided such a polished tool already. And based on my previous SIS experience - while dbox is nice I would suggest avoiding SIS until there are reports of more development. Sdbox will be solid - which is what you want for an archive - though maildir would be the safest. Archives don't need to be rapid-access - they need to be dependable. SIS is wonderful for space saving - but until there's more safety checks built-in I'd suggest avoiding it for production backups. Drives are cheap - lost data, lost time, lost hair, lost sanity...is not.
I'm aware of "doveadm backup", and (although it currently throws up a few errors) it seems like it might be a valid solution for our warm spare server. Our backup servers, on the other hand, aren't supposed to be visible to the production machines, with the exception of the backup machine sshing in to do an rsync each night. We can't install dovecot on them.
The backups don't have to be "visible" to other machines - don't even have to be running IMAP/POP services (I think). And the replication command is run - via ssh (see https://wiki.dovecot.org/Replication) - so what's the problem?
--
Daniel
participants (2)
-
ash-dovecot@comtek.co.uk
-
Daniel Miller