(All info below applies to FOSS Zimbra and Debian 3.1)
Once again, great product, been running on 4.0.5 faultlessly for over 16 months.
Its now the time to upgrade to the latest and greatest, and with help from the forums this is how it went.
I had read on the forums that 4.0.5 -> 4.5.6 was a good upgrade path, so I chose that one. It fell over with an error
ERROR 1005 (HY000) at line 2: Can't create table './mboxgroup32/#sql-6af4_e1.frm' (errno: 150)
Fri Mar 28 19:21:01 2008: Error while running '/opt/zimbra/bin/mysql --user=zimbra --password=Axc9Y2C5ry317rbKPuCLBFbgPzp --database=zimbra --batch --skip-column-names'.
Script failed with code 256: - exiting
UPGRADE FAILED - exiting
After reading the forums it appeared this was an innodb_buffer_pool_size issue. I did use the value in the post of 1992294400, but it never allowed the upgrade to complete. I think (not 100% sure) this value was too big for my 2GB server, so after restoring my 4.0.5 system and testing it. I edited the conf/my.cnf file with a value more to my systems liking => 343597340.
I ran the upgrade again. This time it worked perfectly. I did another rsync backup (to a fresh location, just in case. 43Gb store takes about 1.4 hours).
I then ran the 4.5.11.debian.3.1 upgrade. This also worked without a hitch, apart from the db integrety check which is mentioned on the wiki, and is not a problem anyway, good job wiki.
I am in the process on another rsync backup to a new fresh location, and once thats finished, I will tackle the debian 4.0 OS upgrade and the 4.5.11.debian4.0 upgrade.
Finally (after another rsync backup to a new fresh location again), I will bring zimbra to the latest 5.0. FOSS release.
The wiki has some information on this, but its a little to vague for me :-) I'll just have to cross my fingers!
Anyway, I'll post again with the result of the next upgrades and some more info, this is primarily a post to give anyone else some information who is about the try the same thing, or similiar.
Again, well done zimbra, great product.