Hi,
Currently Zimbra OSS does not support Hot Backup, according to Zimbra. Zimbra says the database state will not be consistent if you use Hot backup. You can though get some scripts that will automatically shutdown all Zimbra processes and perform the backup. One of such script is on
http://swedcore.net. Or rather type backup or script in the forum search.
There a vote going on for Hot backups in Zimbra OSS. Please support.
Cheerio