backup rsync

[Nic Bernstein]

On 08/30/2014 02:37 PM, Patrick Goetz wrote:
> On 8/30/2014 10:10 AM, Simon Matter wrote:
>> I suggest -aH to preserve single instance storage in the backup.
>>
> Does cyrus use a lot of hard links?  I use rsync a lot to create
> snapshot backups, and use hard links across snapshots to preserve space;
> however, for a single instance backup and unless the filesystem includes
> hard links (not normal), then the -H won't do much for you.

Cyrus uses hard links among copies of the same message in different 
mailboxes, when "singleinstancestore: 1" is set, which is the default.  
 From the man page imapd.conf(5):

    If enabled, imapd, lmtpd and nntpd attempt to only write one copy of
    a message per partition and create hard links, resulting in a
    potentially large disk savings.


> Of course one should always use -a.
>
> The biggest concern I have about backing up mail spools is keeping the
> index and message stores in sync while the backup is taking place.  A
> long time ago someone suggested using cyrdump, but when I looked into
> this, I couldn't find any documentation whatsoever.  Is cyrdump a real
> thing, or did I imagine all this?

Are you thinking of ctl_mboxlist?  It allows one to dump the mailboxes 
database to a flat file.  In an out-of-the-box Cyrus installation the 
indexes are stored with the messages in the mailbox hierarchy.  If you 
decide to store meta-data separately, you should simply snapshot that at 
the same time you snapshot your mailstore. At the beginning of this 
thread, Marcus Schopen wrote this example:

      ctl_cyrusdb -c
      ctl_mboxlist -d > mailboxes.db.dump
      stop cyrus
      lvm snaps
      start cyrus
      rsync/var/lib/cyrus/  and /var/spool/cyrus to backup host
      remove snaps

One could simply include any meta-data volumes in the snapshotting process.

Cheers,
     -nic
>
>
>
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-- 
Nic Bernstein                             nic at onlight.com
Onlight llc.                              www.onlight.com
219 N. Milwaukee St., Ste. 2A	          v. 414.272.4477
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