There are a few ways to upgrade your old Sun Messaging Server to the latest release.
1. Using the Coexistence Strategy to Upgrade Messaging Server
2. Using the Side-by-Side Strategy to Upgrade Messaging Server
3. Using the In-Place Upgrade on Messaging Server
Details can be found here.
I was initially into the idea of Side-by-Side Strategy. Reasons being:
1. Does not require extra machines
2. Typically does not involve moving the mailboxes. New version just "points" to the mailboxes and mailbox conversion to the new version is automatic and transparent.3. The binaries of the old version remain intact on the system so you do not have to reinstall and reconfigure in the case of a back out.
So I went ahead for a little POC on my VMware before I introduced the concept to my customer who was looking for a Sun Messaging Upgrade from Comms Suite 5 to Comms Suite 6u2.
Result of my POC: It's a No-Go!
From my finding, the "migrate-config" script attempts to symbolic-link the "config" and "data" directories in the new Messaging Server to the old one.
Looks good so far: We save space by not having duplicate mailboxes via symbolic-linked to the "data" directory. The old configuration are also intact.
However, if you look closely, "config" directory contains a sub-directory "html". This is where Messaging Express is!!
What does this imply?
1. You have a new Messaging Server 7U2 (upgraded from Messaging Server 6.3)
2. However, your Messaging Express has been back-ported to the older release.