I inherited a massive 450 gig mailbox store that houses the majority of our mailboxes in Exchange 2007. This store is apparently heavily fragmented, and it's not unusual for it to take a long time to process larger e-mails. It's also not unusual for a lot of e-mails sent and received to be over 20 megs in size.
That being said, I'm thinking that I really need to move these mailboxes to alternate storage groups to minimize this issue. However, given the large fragmentation and mailbox sizes (most are in the 5 - 10 GB range, some as high as 28 GB), it takes forever to move. I tried to move four 5 gig mailboxes over the long weekend, but had to cancel it after they ran for 48 hours and didn't finish.
With regard to the fragmentation, I've held off on running a defragment, since my understanding is that it would take many days to complete and would even further impact this database. Perhaps my logic here is incorrect?
So, this leads me to my question of what strategy should I take to address this issue while minimizing the impact to the staff actively using it? I've asked staff to start emptying their deleted items and archiving more to help reduce the mailbox size, but I'm wondering is perhaps restoring an old backup to another server and doing some sort of move and merge, or something along those lines is possible?