I have a need to add the CAS role to a working E2k7/W2k8 box that already has MBox & HT roles installed - it has about 1000 small mailboxes on it, so downtime is a major concern. (The domain that 'owns' the server has a need to introduce impersonation to the mailboxes for a piece of CRM software that adds onto Exchange/Outlook. http://msdn.microsoft.com/en-us/library/bb204095.aspx) We're at update rollup 6 and the OS is at SP1.I would appreciate any tips, any experiences anyone has had doing the same, and I would like to confirm that a reboot (or at least a restart of the Store service) is required.Any input is greatly appreciated - thanks very much!

I have added server roles to exchange servers before and did not experience a reboot requirement but ive also known this sort of thing to be varried depending on the system itself. sometimes files are in use and require a reboot and sometimes they arent.as for the services starting, i cant say that ive watched during an installation before but i do know that all services use the topology service so i suppose that would be the risky one.in general i would recommend you plan for at least 30 minutes of downtime for anything like this. you dont want to find yourself between a rock and a hard place with your users/management. Mike Crowley A+, Network+, Security+, MCT, MCSE, MCTS, MCITP: Enterprise Administrator / Messaging Administrator