Backup methods

[Anatoli]

Jason,

What you mention is highly related to the replication backup we were 
talking about in the previous mails. The idea is the same, they 
replicate from master. Then, in a pure replica solution, the replica is 
stopped, a copy of its files (in the native format) is made and it's 
started again to continue replication.

The Cyrus Backups also replicates all data from master, but stores it in 
a different format and has some additional functionality to assist in 
backing up the files, but AFAIK it's not yet complete, e.g. I'm not sure 
it's possible to make incremental backups with it, not sure about the 
SEEN state, the recovery process appears not trivial, etc.

In both cases, a copy of the master data is made, which requires twice 
the space of real usage (Cyrus Backups tries to apply compression on 
stored data, not sure how well it works).

What is really needed, IMO, for SME environments is the ability for 
Cyrus to sync to disk all data, so one can take a hot copy of that data 
with standard UNIX tools and then handle it accordingly. Once a recovery 
is needed, one just copies a backup to the Cyrus dir and starts the 
service. The data would be in the exact same state as when the backup 
took place. This is discussed in the github issue mentioned in the 
previous mail.

*From:* Jason L Tibbitts Iii
*Sent:* Thursday, May 10, 2018 14:10
*To:* Arnaldo Viegas De Lima
*Cc:* Info-cyrus
*Subject:* Re: Backup methods

Cyrus does have an integrated backup system (see
https://cyrusimap.org/imap/reference/admin/backups.html) which I'm not
sure has been mentioned in this thread.  But you still have to have
enough space to keep the compressed backups on disk in order to move
them to tape or whatever archival storage you're using.  There is
discussion of the storage requirements in the documentation.  I don't
think any of it is particularly unreasonable, but I haven't actually
tried it myself.

Technically I don't think you need a separate machine (though that's
simpler); it may just be possible to have a second cyrus server
listening on different ports to act as the replication target.  I
probably wouldn't do it that way anyway; old hardware with some cheap
disk would suffice to stage the backups until they're sent to tape or
wherever.

As for it all being marked "experimental", I'm sure that if bugs were
found (and reported), they would be fixed.  It probably just needs more
testing and back and forth with the devs to flesh out the documentation
and add any missing functionality.

  - J<
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