Я думаю, что, вероятно, сделал бы это с GlusterFS. Настройте кластер серверов хранения, затем смонтируйте активы в сервере хранения на масштабировании frontends и служите оттуда.
Did you properly decommission the old Exchange server? Move all the public folders over? Using Autodiscover properly? Check the https://www.testexchangeconnectivity.com/ site on both valid and invalid clients and note any errors/warnings.
Exchange SCP records in AD and other lingering meta objects will cause issues if you don't decommission it correctly. You'll also be fighting odd issues and random "ghosts" in the future if you don't properly remove Exchange from a server in the "Exchange Org". You can't simply shut it down.
Here's an example link/walkthrough: http://www.hemangshah.com/?p=140
However, if you've never done this before, I'd start by doing some research online about how to decommission it. It isn't hard per say, you just need to be aware that you might run into "gotchas" during the process.
Basically the steps will be (after a known good backup):