Bringing back hub/mb/cas server

Question

Exchange 2010 sp3, 1 DAG, Win2k8 r2 sp1
2 MB, 1 hub main site
1 MB/CAS/hun DR site
for a long time, the Exchange server in DR site has been offline because of no available disk space. now that both the Exchange servers in main site and DR site have the same hd size for the mailbox database, i'm planning on bringing back the DR site Exchange
server.
problem is, the DR site Exchange server have the previous configurations in terms of mailbox database names, sizes. the main site Exchange servers have different database names, sizes. but both have the same drive letters.
question is, when i bring online the DR site Exchange server, how can i make it sync with the new configurations from the main site Exchange servers? should i delete the old mailbox databases in the DR site first, do a file level copy of the mailbox databases
from the main site, and then restart Exchange?

Answer 1

If your database is that large, your best bet for adding a second copy is to use external storage, as you suggest.  However, in order to do this, you are going to need to freeze the database so it doesn't change during the time you are copying the database
and placing it onto your second server.  To do this, you need to add the second database copy (without seeding it - using "Add-MailboxDatabaseCopy -SeedingPostponed" - this will save the log files necessary for the database
copy until it is available to add them) before you start copying your database files, and you will need to copy your database files while the database is offline - you can bring it back online once you have copied it.  I am going to guess
that you don't have the storage necessary to host your log files for an extended time period (more than a week), so you will need to copy the database and get it placed on the second server in a very short time period in order to complete this before your
log drive is full. And if you have a lot of churn in your database, those transaction log files are going to take a very long time to copy across your WAN link so they can be read into the database copy.
An alternate solution you may consider, which won't require that the database be copied manually to the new server, is to add a new mailbox database with copies on both servers, then to move mailboxes into this database. This will allow you to grow the database
gradually, allowing the passive copy to keep up to date with the active primary. You can move the high priority mailboxes to this database first, moving to mailboxes of lower importance over time.
I'll add a final note - if you add your database copy on the weekend, you may be able to seed it across your WAN.  My calculations show that this should take less than a few hours (easily less than half a day), which may be much faster than if you attempt
to copy the database to a USB device and transport it to the second datacenter.  That WAN connection is going to be saturated while this copy goes on, which is why I recommend doing it on a weekend.