We are wondering about the requirements for a possible Zimbra installation of about 300,000 users, and were going for the Open Source version. We have been reading the recommended settings and have a few doubts about it.
First, it's not really clear how the multiserver installation works. In our imaginary setup, we would have 1 LDAP "master" server, 2 LDAP replicas and 2 mailbox/store servers per replica. 2 MTA servers would be balanced from the outside using LVS or some other technique pending of decision.
Our question is: from what we've read, it seems that each mailbox server is a full copy of the other. This would mean that we had to multiply by four the disk space alloted for the email accounts. So, if we allocate 100MB for each account, we would have 300,000 x 100 x 4 = 114TB (approx.).
Are we misunderstood? What should be the proper setup for "splitting" the 300,000 accounts among four or more mailbox servers?
Thanks in advance.