Thoughts about adding more than the 8GB of recommended RAM?

[cajuntank]

I have had my Exchange 2007 (SP1,RU4) single server up and running for almost a year with no major issues to speak of. Everything was built and designed using HP's sizing utility for my user count and storage requirements. It flowed right along with Microsoft's recommendation on the amount of RAM as well for single server/multi role installs of 8GB, so that's what I currently have. After many budget issues, I have finally gotten my backup solution in place running Microsoft's DPM 2007 which I am really liking so far (it was about 10% of the cost Symantec was going to cost me since I get educational pricing). I am also about to add to my storage (DAS) to allow for more mailbox space and also for LCR.

With these two added processes, is 8GB still enough or would it actually hurt the performance of the system to add another 8GB to get to 16GB of RAM?

 

[58sniper]

Not enough info to say. But if you use perfmon to monitor your system resources, you should be able to tell if your system is being taxed.

You can also do the sizing again with the proposed higher mailbox limits and LCR factored in.

I've always felt like RAM was like money. You can never have too much.

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/

 

[cajuntank]

I just thought I remember reading something some time a while back about muti-role installs and that 8GB recommendation... it actually being detrimental and hurting performance having more than the 8GB (I might be confused and thinking of something else). I am approaching 600 users and have not seen anything performance-wise to flag me of an issue; but I haven't implemented LCR yet either, just the DPM agent. So while I had some money released from my budget, I was going to invest some more into that server and was thinking about adding more memory along with storage.

 

[Zelandakh]

8GB is just static.

Here is an extract from one of my blog articles:

Taking it as read that you know you need 2GB of RAM for the mailbox role, another 1GB for other roles, how much extra RAM do you need? Any?

The answer is yes – you need more RAM once you have users connecting. 2MB per light user, 3.5MB for a medium user and 5MB for a heavy user. Scale that up across your enterprise and even with 1,000 heavy users on a mailbox server means you only really need 7GB of RAM. However, there is another consideration – storage groups. It used to be the case that Exchange 2007 needed 0.5GB per storage group but this has now reduced.

Old calculation 0.5GB per storage group
New calculation 2GB plus storage groups/4 except for 1-4 storage groups where you only need 2GB.

So, when deciding how much RAM you need for Exchange 2007 with 48 storage groups on a dedicated mailbox server with 5,000 heavy users, you need:

Exchange requirement: 2GB
Storage groups requirement: 12GB
User requirement: 25GB

That makes 39GB of RAM so you’ll need Windows Enterprise Edition.

 

[xmsre]

Don't forget "I have finally gotten my backup solution in place running Microsoft's DPM 2007 ". The MS VSS provider consumes RAM as well. Depending on your protection plan, it could add up to a lot.

See:

http://technet.microsoft.com/en-us/library/cc755419.aspx

 

[baddos]

Are you running DPM on your exchange server or just the agent?

 

[cajuntank]

Sorry for not responding sooner, been making rather merry. Thanks guys for all of you responses... I did have someone point me to this...

http://technet.microsoft.com/en-us/library/bb738124.aspx

where it clearly states for multiple role install "8 GB plus from 2 MB to 5 MB per mailbox. This is variable based on user profile." Up to a maximum of 32GB.

Also, I'm just running the DPM agent on the Exchange server, but now am having second thoughts after having gone through a demo of Replay from a company called AppAssure... it was very cool and makes DPM look like a little baby comparitively.

 

[xmsre]

The limitation is a limitation of the MS software VSS provider. If you're using the software provider, you'll need to allow for the RAM for the number of snapshots you have in place.

 

[Zelandakh]

Your original question is about 16GB harming the performance...No. It will continue to improve.