Exchange Memory Utilization

Recently I had someone ask me what the recommend maximum settings were in Exchange 2010 before getting a performance hit. After I pulled up the appropriate TechNet Articles for him, I decided I'd go ahead and post them here.

Here's the Article for Exchange 2010.

Memory configurations for Exchange 2010 servers based on installed server roles

Exchange 2010 server role	Minimum supported	Recommended maximum
Edge Transport	4 GB	1 GB per core (4 GB minimum)
Hub Transport	4 GB	1 GB per core (4 GB minimum)
Client Access	4 GB	2 GB per core (8 GB minimum)
Unified Messaging	4 GB	2 GB per core (4 GB minimum)
Mailbox	4 GB	4 GB plus 3-30 MB additional memory per mailbox: The total required memory is based on the user profile and database cache size. For more information about how to determine the total required memory, see Understanding the Mailbox Database Cache.
Client Access/Hub Transport combined role (Client Access and Hub Transport server roles running on the same physical server)	4 GB	2 GB per core (8 GB minimum)
Multiple roles (combinations of Hub Transport, Client Access, and Mailbox server roles)	8 GB	4 GB plus 3-30 MB additional memory per mailbox: The total required memory is based on the user profile and database cache size. For more information about how to determine the total required memory, see Understanding the Mailbox Database Cache.

Here's the Article for Exchange 2007.

Memory configurations for Exchange 2007 servers based on installed server roles

Exchange 2007 server role	Minimum per server	Recommended	Maximum per server
Edge Transport	2 GB	1 GB per core (2 GB minimum)	16 GB
Hub Transport	2 GB	1 GB per core (2 GB minimum)	16 GB
Client Access	2 GB	2 GB per core (2 GB minimum)	16 GB
Unified Messaging	2 GB	1 GB per core (2 GB minimum)	4 GB
Mailbox	2 GB; also depends on number of storage groups (For information, see later in this topic.)	2 GB plus from 2 megabytes (MB) to 5 MB per mailbox. This is variable based on user profile. For more details, see "Mailbox Server Role" later in this topic.	32 GB
Multiple roles (combinations of Hub Transport, Client Access, Unified Messaging, and Mailbox server roles)	4 GB; also depends on number of storage groups (For information, see later in this topic.)	8 GB plus from 2 MB to 5 MB per mailbox. This is variable based on user profile. For more details, see "Mailbox Server Role" later in this topic.	32 GB

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Dustin Shaw
VCP