Man i thought i made it clear.
the only real way is todo a cold backup.
zimbra stores on ldap - on mysql - and on the filesystem
thats why you canīt do an easy cluster with it - even with replicationg mysql and ldap and mirrored filesystem this doenst work (you need to mirror the redologs)
so i strongly suggest not to try such a partly backup
about the rest bug - someone ment that tomcat messes up streams after a while - anyway its confirmed you cannot backup and restore big mailboxes with rest
i had htis problem frequently while migration process - plan was to creat parallel accounts todo the outlook import work and then add the imported to the running accounts with rest
turns out you gonna loose mails with that - simply try it out
take a 2 gig mailbox make a rest download and restore it to an test mailbox - then count mailcount and size on both boxes
so really - no matter how make a cold backup
as described you can make a hot prebackup to reduce the amount of data needs backing up
at the end if system crashed totally you method takes a way longer to restore and bring it backup, its way more complicated and got a lot of risk involed of data inconsistence
easiest way is todo a double rsync (thers a script out there) it mirrors a hot prebackup on the same system - then do the cold backup (minimum downtime) then rsync the mirrored data to an offsite server
every other method of an hotbackup wont go easy..
btw theres some discussions for a long time because of the aweful method zimbras stores data - as said bevore - it a big thing of cluster - thats why theres an extra backupmethod implemented in networkedition which had a lot of bugfixes recently -
in short it isnt that easy to backup zimbra hot / or cluster it - in other words dont try this at home
