CPU Cores: the Recommended Processor Core Ratio is : ‘Mailbox’ cores : ‘HUB/CAS’ cores ====> 1:1
EG: Mailbox server will be implemented by 16 core processors; each hub server minimum processor should be 8 cores
RAM: RAM should be estimated by 2 GB of RAM per processor core ((4/8 GB minimum total))
EG: Hub servers will use 8 x processor core, using the above equation; 2 GB of RAM should be added for
each core processor: 8 processor core x 2 GB RAM =16 GB RAM per server.
CPU: Generally 4 x processor core server provides a good balance between price and performance, and
should be able to host several thousand mailboxes.
EG: 5000 user can be hosted on one of the mailbox servers.
The user profile send and receive 50 message per day will require 1 megacycle on the active mailbo
= 5000 x 1 megacycle = 5000 megacycle.
Adding 10% for each copy of the database (only 1 copy will be available) = 500 megacycle.
The estimated required megacycles per server = 5500
Sizing used primarily for budgeting purposes can be accomplished by assuming that 1,000 active average
profile mailboxes will require a 1 x processor core, this equal to 5 cores per server.
The recommend CPU requirements for each mailbox server will be 2 (physical processors) x 4 (cores) = 8
Active Directory Server and Mailbox Server Ratios
The recommended number of Active Directory directory servers in each site containing Exchange 2010 Mailbox servers or users depends on the number of processor cores in each computer running the Exchange 2010 Mailbox server role and the hardware platform on which Active Directory is running. Specifically, consider the following scenarios:
- 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. To achieve the 1:8 ratio, you must have enough memory installed on the directory server to cache the entire Active Directory database in memory. To check the size of your Active Directory database, examine the NTDS.DIT file on a global catalog server. By default, this file is located in %WINDIR%\NTDS.
In the preceding ratios, it’s important to note that this is a ratio of processor cores and not processors. Thus, a dual-core processor counts as 2 when calculating the ratio. The ratio difference between 32-bit and 64-bit is due to the larger amount of memory that a 64-bit operating system can support as compared to a 32-bit operating system.
For Exchange 2010, we recommend that you deploy one 32-bit global catalog server processor core for every four Exchange 2010 Mailbox server processor cores, or one 64-bit global catalog server processor core for every eight Exchange 2010 Mailbox server processor cores. Although other server roles will influence the number of global catalog processor cores required, the Mailbox servers that are deployed influences the deployment of each of the other roles, so basing the number of global catalog processor cores on Mailbox server processor cores will suffice.