RAM Requirement in SBS2011

Hi,

 I am about to order a new DELL server 2.4Ghz E5620 Xeon CPU that comes with 12GB of RAM and with a couple of SAS HDs ( I am going to add 4 more 600GB SAS HDs).

 There won't bet SQL server running on this box, but going to run EXCHANGE 2010 with about 20 mailboxes w/ a total store size of 60GB and expect that to grow to probably 120GB - 200GB in the next 5 years. Other than Exchange, there are 20 users who use Office Apps (WORD/EXCEL/ACCESS).

  How much memory would be adequate? I like to hear from people who installed SBS2011 on a new server box. This DELL R710 rack server can have up to 192 GB.

Thank you in advance.
sgleeAsked:
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Philip ElderConnect With a Mentor Technical Architect - HA/Compute/StorageCommented:
Each CPU has a dedicated memory channel (there are 3 channels per CPU).

3x 4GB per CPU = 24GB of RAM.

Having one (1) 4GB stick of RAM per channel across all six channels will give the best performance and value for the money spent.

I highly doubt going beyond 24GB would create any real benefit beyond the $$$ spent.

Philip
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Philip ElderTechnical Architect - HA/Compute/StorageCommented:
Exchange 2010 likes RAM and lots of it. This is primarily how the Exchange development team restructured Exchange to run _lots_ of mailboxes on _one_ SATA hard disk.

12GB would be the starting point. 24GB would be better.

However, it would also be preferable to have both CPU sockets populated. That way _all_ memory channels can be utilized for that additional RAM. The server will have better all around performance.

One thing to keep in mind: Dell has to keep that second CPU on a shelf somewhere over the life of the server as a "just in case". So, make sure to check out the standalone cost of the CPU versus dropping in a pair at configuration time (probably ~2-3x cost of pairing at config).

Philip
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sgleeAuthor Commented:
MPECSInc:

 I understand 24GB or better part and two CPUs are better than 1 CPU.
 But I don't quite understand this ... "One thing to keep in mind: Dell has to keep that second CPU on a shelf somewhere over the life of the server as a "just in case". So, make sure to check out the standalone cost of the CPU versus dropping in a pair at configuration time (probably ~2-3x cost of pairing at config)"?
 Can you rephrase it for me?
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Philip ElderTechnical Architect - HA/Compute/StorageCommented:
Order the server with 2CPUs today the adding the CPU costs $1000 (example number).

Order that second CPU in 18 months due to increased performance need and CPU costs $3000.

Check the off the shelf price for adding that additional CPU if there is any possibility of needing it in the future.

For dual socket and quad socket servers we always populate all sockets in the initial configuration.

Philip
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Philip ElderTechnical Architect - HA/Compute/StorageCommented:
One more thing: For CPUs to work in pairs both must be identical.

Over the lifetime of a CPU the manufacturer can make slight or even significant changes to the internal structures and logic of the part.

So, buying an E5620 later on down the line from a third party (not Dell) and dropping it into the server may very well not work due to the differences in CPU family/stepping.

As Dell and other Tier 1s know this they keep the correct CPUs on the shelf just for those cases where someone wants to add a second CPU. The cost of keeping that CPU sitting on the shelf is _expensive_.

Philip
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sgleeAuthor Commented:
Thanks for clarifying it.
What you are saying is that if I buy the R710 with 1 CPU populated and leave 2nd CPU slot empty, I can alway buy 2nd CPU at a cheaper later (when needed)?
But then if INTEL changes the spec on the same CPU slightly, it may not work?
Also what I am hearing here is that on two CPU socketed servers, it is better to populate both CPUs at the same time for performance standpoint?

I was going to just get 1 CPU with R710 originally based on the current needs.
Do you think I need two CPUs from the start?
How much of performance would I loose if I go with 1 CPU with R710?
I considered R710 because of 6 HDs slots in RACK format, not because of dual CPUs.
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Philip ElderTechnical Architect - HA/Compute/StorageCommented:
What you are saying is that if I buy the R710 with 1 CPU populated and leave 2nd CPU slot empty, I can alway buy 2nd CPU at a cheaper later (when needed)?

No, I am saying that it may be two to three times more expensive to by that CPU from Dell at a later date.

But then if INTEL changes the spec on the same CPU slightly, it may not work?

Yes.

Do you think I need two CPUs from the start?

It is a matter of looking at current needs versus what those needs will be over the life of the server. It is always better to build something a bit more powerful than what is currently needed just in case there is an unaccounted for increase in server demand. YMMV.

Philip
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sgleeAuthor Commented:
OK. If I buy two CPUs with 32GB of RAM which is maximum specified by Microsoft for SBS2011, will both CPUs utilize this pool of 32GB of RAM automatically?
Or do I need to populate 32GB for each CPU; therefore buy total 64GB of RAM?
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sgleeAuthor Commented:
MPECSInc:,

  Per your advise, I will get 24GB memory with 2 CPUs.

  Thanks for you advise.
 
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