There has been a lot of discussion surrounding the use of rsync for mirroring the real time scanner backed up files to a secondary/and or tertiary system. I would like to explore a couple of alternative approaches and see whether they could be more efficient and less likely to potential file inconsistencies.
The first would be the use of DRBD and GFS to create a clustered LVM specifically for the /opt/zimbra/backup/zextras directory. As long as the systems have a dedicated giga link between them then it could be pretty good for setting up a hot standby.
The second approach would be the use of Inotify: Efficient, Real-Time Linux File System Event Monitoring to monitor the backup directory for filesystem changes. As it is able to trigger on a committed write then there should be no fear of synchronising a partial file. Obviously it would need to be scripted; perhaps use Tatsuhiko Miyagawa / Filesys-Notify-Simple - search.cpan.org but it at least would only transfer files when something has been written. That would certainly negate the necessity of a cronjob running every through minutes and putting additional load on the system.
These are just some muse ramblings to hopefully fuel some further discussion on this subject.
Thanks.