Processor and Memory Recommendations for Exchange 2010

Being on 32 bit platform Exchange 2003 always had limitations of memory sizes though not for the processors. Yet, the standard processor ratio for DS:Exchange can significantly affect your Exchange Server performance as well as the end user experience. You can recall that Microsoft recommended 1:4 processor ratio for an Exchange Server 2003 deployment. Now here in this ratio Microsoft recommended using at least 1 core of CPU for your domain controller/global catalog if you have an exchange server which runs on a CPU having 4 cores in it.

These recommendations have few more additions since Exchange 2007 and a bit for Exchange 2010 too. Due to the x64 architecture of both products and the platform’s capacity to address more memory along with Exchange’s its own bifurcated server roles it is necessary to review it. Well, the recommendations per server role for Exchange 2010 are below:

Server role Minimum Maximum Recommended
Edge Transport 1 x processor core 12 x processor cores 4 x processor cores
Hub Transport 1 x processor core 12 x processor cores 4 x processor cores
Client Access 2 x processor core 12 x processor cores 8 x processor cores
Unified Messaging 2 x processor core 12 x processor cores 4 x processor cores
Mailbox 2 x processor core 12 x processor cores 8 x processor cores
Multiple server roles (combinations of Hub Transport, Client Access, and Mailbox server roles) 2 x processor core 16 x processor cores 8 x processor cores

Table 1

Apart from above recommendations you still need to maintain the ratio of processor cores per server role to each other below is another table which talks about it.

Server role ratio Recommended processor core ratio Memory Per core
Mailbox:Hub 7:1 (no antivirus scanning on Hub)

5:1 (with antivirus scanning on Hub)

1 GB for each core on HT
Mailbox:Client Access 4:3 2 GB for each core on CAS
Not applicable for Edge Refer Table 1 1 GB for each core

Table 2

Again, the old days still have their importance in life. Domain controllers providing services to an exchange organization should still maintain the 4:1 ratio if you have a domain controller running a 32 bit operating system. This scenario changes a little bit for a domain controller running a 64 bit operating system. The ratio for an domain controller with 64 bit OS is 1:8. Here the exchange server’s CPU cores are for every server role. That means if you have a 3 different servers named MBX – mailbox server role, CAS – your CAS server role, HT – your HT server role, and UM – your Unified messaging server role having 4 cores in each which should be 16 cores in total then you should have at least one domain controller running 2 cores of CPU. For more information on choosing a right CPU for your 64 bit infrastructure you can refer the supported processor manufactures websites. Intel or AMD

Addition to this, each mailbox server should have 4GB of memory plus 2-10MB per mailbox, based on if the mailbox is in light, average, or heavy use. To calculate the memory requirement and storage requirement for the mailbox server role you can always refer the mailbox storage calculator: http://msexchangeteam.com/files/12/attachments/entry453145.aspx

References:

http://technet.microsoft.com/en-us/library/dd346701(EXCHG.149).aspx

http://technet.microsoft.com/en-us/library/dd346699(EXCHG.149).aspx

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