With Exchange 2010 ,No need to worry about the overlapping that may happened between the online maintenance window and Exchange Database backup window …. Even if you have big databases that may required long time to be backed up , why?
In Exchange 2010, the architecture for online defragmentation has changed. Online defragmentation was moved out of the Mailbox database maintenance process. Online defragmentation now runs in the background 24×7.
You don't need to configure any settings for this feature. Exchange monitors the database as it's being used, and small changes are made over time to keep it defragged for space and contiguity. Online defragmentation is also throttled so it doesn't have a negative impact on client performance
This option works well for larger databases, up to 2 TB, where you need more time to checksum the databases
So run your backup job any evening time and enjoy your life with Exchange 2010
http://technet.microsoft.com/en-us/library/bb125040.aspx
http://technet.microsoft.com/en-us/library/bb691410.aspx
Posted 03-31-2010 1:45 PM by Samer AlOtaiby