Exchange 2010 servers sizing recommendations

For all who are involved in Exchange 2010 sizing you can find here a detailed guidelines about the ratio of Hub/CAS and Mailbox servers resources .

The basic guidelines are as follow , based on the number of processor’s cores :

Server role configuration	Recommended processor core ratio
Mailbox : Hub Transport	7:1 (no antivirus scanning on Hub Transport server) 5:1 (with antivirus scanning on Hub Transport server)
Mailbox : Client Access	4:3
Mailbox : Client Access and Hub Transport combined role	1:1

In addition, for Active Directory / mailbox server ratios :

• If Active Directory is running on the x86 platform (32-bit), the recommended ratio of Active Directory directory server processor cores to Exchange 2010 Mailbox server processor cores is 1:4.
• If Active Directory is running on the x64 platform (64-bit), the recommended ratio of Active Directory directory server processor cores to Exchange 2010 Mailbox server processor cores is 1:8

Enjoy Exchange 2010 servers sizing