Exchange -- logical free space / migration question

We are migrating from SBS 2003 to SBS 2008.   Our contractor is using a migration tool, and "middle-man" server to migrate everything.  

We had nearly 60GB in our exchange DB, and the migration was at about the 32 hour mark when my boss called it off.  (I think we would have been better to just bit the bullet and let it finish -- was probably only going to take another 5-10 hours)

Anyway -- we just archived 2/3 of the stuff out of the exchange DB.  So we are now at 20GB.  (though the physical files are 85GB, with 65GB logical free space)

Do we need to do an offline defrag before the next migration attempt, or should it just skip over all that logical whitespace?

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Brian PiercePhotographerCommented:
It would be prudent to do an offline defrag - otherwise you will just end up copying the 'white space'
An offline defrag is a good idea before the next migration. it should speed up the process and correct issues before they occur.
XetroximynAuthor Commented:
The offline defrag is supposedly going to be an issue.  We will need an external drive because there is not enough space on the old server.  And they say it could take 24-30 hours to do the offline defrag.  

Now -- if it speeds the migration, that is all well and good.  But then we have to add the down time of the offline defrag, and am just skeptical we will really come out on top.  

Thoughts with this in mind?

p.s. we run 7 days a week, 9am-11pm, so down time is is a nuisance no matter when it is.

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From experience the time is relative to the reported file sizes of the EDB/STM

And from experience it is usually about 6GB per hour but obviously depends on your specification.
Brian PiercePhotographerCommented:
You are going to have to do an offline defeag at some time - or live with a permanently degraded database and suffer the loss of disk space - you might as well do it before you move the file - it WILL speed up the data transfer.
Assuming the offline defrag would go faster on the new server, I bellieve the asker is wondering whether spending up to 14 hours to do on offline defrag prior to the migration is going to save enough time to justify the down town time.

Not only will the offline defrag reduce the database size considerably it could resolve issues that would make an un-succesfull maigration.

I would say yes it is worth the time.
If you have the space you could set up a new information store and move all your mailboxes to the new store. You will be left with one database that has defragmented and another that is all white space.  Then you can delete the old empty database, or defrag it if that makes you feel more comfortable. Make sure to run your full backup before and after the move.  You will also want to use circular logging while the move is taking place or you will definately run out of space.

The only down time that will be experienced will be on a per user basis as their mailbox is being moved and you can run this process throughout the week.  However keep in mind that if you have circular logging enabled you will be at risk of losing a lot of data.

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XetroximynAuthor Commented:
This sounds like a good idea.  just to make sure I am clear.  So on the old server I can set up a second information store and move the mailbox's one at a time? (or perhaps in groups at night)  They stay on the same server, just moved to a different physical DB on the same server.

And to confirm -- can this be done on SBS 2003, or might that limit me to one exchange DB?

About the logging, what if I have a very large external drive for the logs.  Like 1 or 2TB.  do you think I could do non-circular logging then?  

(for reference it is 20GB of data with 65GB whitespace.  About 60 mailbox's, maybe 30-40 actually really used, a total about 260K Items)

Yes, you are correct.  You would want to find all your users with ADUC and select a chunk of them.  You would then right click and use the exchange task wizard to move them to the new database.  Exchange will move 4 mailboxes at a time.  Users will still have access untill exchange begins to move their mailbox.  You may get errors moving that will likely be from the user having outlook running.

I tried finding the database limits for SBS 2003 but I have been unable.  My gut tells me you are limited to 2 databases however I cannot say that with confidence.

For the logs, that would be plenty of space.  You will probably want to do a full backup to flush your old logs prior to moving them.  If time and resources are available you should do a full backup of both databases before and after each night of moving.

On my old network, when we did our migration to 2003 EE we stayed with the default first storage group.  I had later decided to reorganize, creating 4 storage groups.  We did the majority of our moves throughout the day.  It caused a loss of service for 4 people at a time which in my mind was acceptable.  We had around 3000 users with about 450GB of mail.
Also, when we did our migration, I was not there for the bulk of it however I can tell you that we used the exchange task wizard to move all the mailboxes from the old exchange to the new.
XetroximynAuthor Commented:
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