Zimbra's backup system seems to be insane. For example, I have 26 users. All but 7 of those users are very, very light users... maybe 500 messages total max. Almost no attachments.
The rest of my users are what I would call moderate email users. Some have a history of emails going back 5 years, but those archives are purged and generally only important emails are kept.
So, about 10 weeks ago I noticed that Zimbra's backup directory was a bit weird. First, before doing this I purged all backups from the backup dir. I performed a fsck just to be sure. I've verified that the drives seem to read and write at normal speeds.
However, well... here's an example:
xxxxxx:/opt/zimbra/backup# time ls -Rf > /tmp/it
Yes, that's 48 minutes. Now I'll get rid of all the leading directories and spaces in the output, leaving effectively only filenames:
# grep -v "^\." it | grep -v "^$" | wc -l
Ah! Almost a milion filenames?! Er, what's up here guys, that was ONE full backup! Oh, and yes, I've rebuilt all the mailboxes too, just in case that would make a difference.