We went through (still not 100% finished) a single server to multi-server migration. It appears that you have it correct as you describe it. Just to clarify and use what we did as an example:
- We had a single server (zimbra.domain.com) which is what users always went to (for IMAP, SMTP, webmail, etc.)
- We setup three mailstores (zstore1.domain.com, zstore2.domain.com, zstore3.domain.com)
- We setup that single server as a proxy as well (so when I started moving accounts to different mailstores, each user could still use the original server URL (zimbra.domain.com) with no issues.
- We then setup two proxy servers (zproxy1.domain.com, zproxy2.domain.com).
- We set the public service hostname for each server as zimbra.domain.com
- We pointed DNS (round-robin) for zimbra.domain.com at the two proxy servers.
By using the zimbraPublicServiceHostname, we made sure that even if users were going to one of the proxy servers, the URL in the address bar remained zimbra.domain.com.
State University of New York at New Paltz