Gonna slowly turn this into a larger script eh?
I made some slight edits for ya to look at - the reasons can be found in the history notes:
Open Source Edition Backup Procedure - History - Zimbra :: Wiki
(posting here because I don't know if you both have minor edit emails turned on)
Side track: If you want some fun checkout
rotating rsync incermentals & even easier try a
rsnapshot setup - it saves a boatload of space
Use it in a more live mode via a crontab and you should really end up with all the important stuff (though for the first 'full' of the entire set that you make be sure that zimbra's stopped) - or throw it into an existing cold script/crontab.
To grab 'exactly what's going on with your box' you could run it on redologs...
zmprov mcf zimbraRedoLogDeleteOnRollover FALSE (then reboot so it applies) should get you decently started.
You can adjust the size by modifying zimbraRedoLogRolloverFileSizeKB (102400 is the 100MB default).