This is Exchange 2013 with DAG setup, so I know reclaiming whitespace isn't an option. The problem I have is the amount of time required to procure more capacity in the SAN and keeping the drive from running out of space. There are two databases on separate Windows partitions.
E: 2 TB with 50 GB Free - DB1
F: 950 GB with 125 GB Free - DB2
Will migrating mailboxes from DB1 to DB2 slow the growth of DB1 by creating whitespace, or is that whitespace completely unusable without a defrag?