Procedure for Upgrade and Redesign

[anhedonia]

Hi,

I'm currently running a 6.x monolithic server (ie one machine that runs the entire Zimbra suite), and am wanting to switch over to a multi server system. I am also wanting to upgrade to 7.

My options are
1) Upgrade the current server to 7, then later split it out into a multi-server installation
2) Split the current server out to a multi server installation, and upgrade it during another maintenance window
3) Do everything at once

I am currently leaning towards 3, which will basically involve the following :

Install fresh servers (using Zimbra 7 running on RHEL) that will become
1) LDAP
2) MTA / Proxy (combined for now)
3) Mailbox host

Upgrade the current server to 7
Change it's hostname and ip
Link the new LDAP server to the current server as a replica, wait till everything replicates over, make it into the master LDAP server
Bring up the new mailbox host
Bring up the MTA/Proxy box using the old server's hostname/ip (making sure it see's both the new mailbox host, and the old server)
Start transferring accounts over to the new mailboxd at my leisure.

I'm just a little worried about any incompatibilities between the old database schema, and the new one (I'm not wanting to upgrade the database on the old server, as rough calculations have told me it could take around 6 hours)

Can anyone see any logic flaws in my upgrade procedure ?
The reason I'm wanting to split the server out now, is we are estimating rapid growth in the future, and i would prefer to bring up new servers (actually VM's running under Xen, I don't see the advantage currently to switching over to vSphere) than extend the existing one. (Mainly for ease of backup)

Would it be a saner idea to split out to a multi-server setup and then wait for everything to settle down before upgrading ?

[gcakici]

Have you accomplished the redesign? How did it go? Which way did you choose? I'm on a project like that and i want to know did you successfully end up with the redesign.

Thanks
Gokalp