hot backups

[Warren Turkal]

I know this is a perennial question, but I wanted to see if the following 
strategy would work for a hot backup for Cyrus.

1. SIGSTOP all process with the pgrp of cyrmaster
2. ctl_cyrusdb -c
 - optionally ctl_mboxlist -d here
3. create lvm ro snapshot
4. SIGCONT the processes with pgrp of cyrmaster
5. mount the snapshot
6. backup the snapshot
7. umount the snapshot
8. remove the snapshot

I guess my only question is does cyrus do database commits with ACID 
semantics? If it does, then SIGSTOPping and ctl_cyrusdb -c should cause it to 
be as quiesced as possible. Creating the snapshot and SIGCONTing the 
processes should happen fast enough that TCP connections shouldn't time out.

As an aside, does an lvm2 snapshot have a maximum size. Anything above 512MB 
seems to be failing for me.

wt
-- 
Warren Turkal, Research Associate III/Systems Administrator
Colorado State University, Dept. of Atmospheric Science