I've been tasked with designing an EV10 environment for a new customer of ours. a quick rundown on client environment

• Exchange 2003 (2), migrating to Exchange 2010 in a new forest (Green fields implementation. User accounts will not be migrated)
• Number of user mailboxes: 900
• Number of shared mailboxes: about 600
• Average user Mailbox size: 2.8GB (!)
• Average shared Mailbox size: 1.5GB
• about 400GB in PST files

The customer also requires Discovery accelerator

I'm not concerned about sizing of databases or storage, I've written my own calculator and I'm happy with it.I have read the new EV 10 system requirements, and this is where I have concerns. Based on my experience, anything above 4vCPU you start running into possible CPU contention issues, with sometimes appalling performance as a result (this is very evident on SQL servers).

So, my suggested solution is 1 EV server, 1 Indexing server, 1 DA server, server specs, below

EV server 1 (Storage)

• Windows 2008 R2
• 4 vCPU
• 16 GB RAM

EV server 2 (indexing)

• Windows 2008 R2
• 4 vCPU
• 16 GB RAM

EV server 3 (DA)

• Windows 2008 R2
• 4 vCPU
• 16 GB RAM

Note: SQL backend is share clustered physical servers, hence reason I've purposedly left out.

While we could run a single 8 vCPU server for storage and indexing, I believe we would get better performance out of the specs above. Virtual machines would run on separate hosts. What are your thoughts on this?