Just thought I would let you know the results of the move. We were a bit concerned about the loss of SIS, but we had 4 Databases of varying sizes across the org and total DB size including STM files was 171 GB on Exchange 2003 SP2, after moving all mailboxes the mailbox store with log files on the Exchange 2010 is 178 GB.
I would suspect that in a single DB environment a loss of SIS would have a much larger impact on the actual DB size. A number of you asked about this directly, so I thought I would respond publicly. On our ESXi server running 16GB ran and allocated 2 processors to the task we are hardly denting the box other than when we were doing mailbox transfers. We are also running Ninja and BES 5 (latest updates) I might increase the memory on the box but I want to run some baselines to see if increasing the memory has any dramatic benefit. Thanks everyone for your help, I learned a ton and after reviewing my notes and making a more detailed migration plan we are going to begin migrating a lot of clients with old 2003 boxes in need of migration. Greg Sweers
