Another 2.4 upgrade horror story

[Wolfgang Breyha]

Janne Peltonen wrote, on 25.09.2012 15:34:
> Could you elaborate on that? I considered that option, but seeing as moving
> even a couple dozen users from a backend to another using RENAME takes hours
> and one backend contains thousands of users, I decided to just live with the ~1
> day of unbearable slowness. Or do you know of a fast way?

Time was not the limiting factor for us. Availability and safety of our
mailboxes was. Nobody can guarantee you that the migration works out
flawlessly. If moving one mailbox fails I have troubles with exactly one
mailbox. If reconstruction of one mailbox fails while migrating hard from 2.3
to 2.4 your system is down even longer. And we had a couple of problematic
mailboxes as partly documented on this mailinglist;-)

We had 5 backend stores and have 6 now. Complete migration of our 150k users
with ~22TB took about 3 or 4 month. Including building the machines,
requesting storage, etc...

But you can't have less headache then moving mailboxes from backend to backend.

In detail I
*) check for active sessions on the mailbox
*) lock the mailbox by denying access via userdeny.db
*) move the mailbox
*) unlock it

Greetings, Wolfgang
-- 
Wolfgang Breyha <wbreyha at gmx.net> | http://www.blafasel.at/
Vienna University Computer Center | Austria