The first question I would ask is: why do you want to do a defragment?
Will you recover more than 30% of storage space? Have you been advised to by PSS?
If not, then I wouldn't bother. Taking Exchange offline to do a defrag, without a good reason, is just a waste of time and processor cycles.
Besides which, given sufficient disk space, doing a move-mailbox to a new storage group is MUCH less intrusive.
From: exchangelist-bounce@xxxxxxxxxxxxx [mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of Danny
Sent: Thursday, November 15, 2007 12:10 PM
Subject: [ExchangeList] Exchange offline defrag timeframe
Any idea how long and how much disk space I will need to offline defrag the following platform?
Server: Xeon 3.6Ghz, 4GB RAM, RAID 5 on 4 15K RPM SAS drives
Exchange Server 2003 SP2
Primary Storage Group = 90GB
Secondary Storage Group = 15GB