Comments on: SQL Server memory configuration

By: stephanie-b

stephanie-b — Wed, 15 Feb 2012 14:51:39 +0000

Thank you for such a clear and concise post on this subject.

I wasn’t even aware of DBCC Memorytstatus, as it is not documented in BOL.

Regards,
Stephanie

By: Ajmer Dhariwal

Ajmer Dhariwal — Mon, 23 Jan 2012 21:18:03 +0000

Good question. Although SSIS and SSAS from part of the SQL Server stack they have completely different memory architectures so you would have to monitor their peak memory usage by reducing SQL Server’s max memory settings to ensure SSIS and SSAS have enough room and to see how high their memory usage goes under peak loading.
In my experience on servers where we had to run SSAS/SSIS alongside SQL Server (something we tried to avoid if they were high load systems) the SSIS/SSAS process will peak at a certain level depending on the workload thrown at them and we would adjust SQL Server’s memory settings accordingly, or just add additional memory if the peak uses of the SSIS/SSAS processes took up too many resources. I’d also highly recommend adjusting SQL Server’s max degree of parallelism settings otherwise SQL Server will saturate the CPUs denying SSIS/SSAS cpu time when any e.g. data loading/transformation is taking place. You can also look at SQL Server’s CPU affinity settings (bearing in mind SSIS/SSAS don’t yet have similar functionality).

By: rick

rick — Mon, 23 Jan 2012 17:10:40 +0000

Hello, very good post, thank you.
Question: how do you consider and factor in memory needs of SQL services such as SSIS, SSAS etc? These applications utilize memory outside of the SQL mem manger’s control, yes?

thank you for insight into this question.
Rick

By: Ajmer Dhariwal

Ajmer Dhariwal — Fri, 13 Jan 2012 13:25:32 +0000

Yup, you're hitting that infamous bug. Apply the last CU for SP4 (build 2187).

By: Adam

Adam — Fri, 13 Jan 2012 02:26:17 +0000

Is it because of the bug you mentioned in your post or is there any memory cap for sql 2000 on windows 2003?

By: Adam

Adam — Fri, 13 Jan 2012 02:23:34 +0000

Hi Ajmer,

I would like to clarify my doubts related to memory.
The server is question is Windows 2003 32 bit enterprise Service Pack 2 (physical memory is: 64 GB) and has sql server 2000 SP4 (8.0.2039) 32 bit Enterprise.

The AWE and /PAE switch are enabled and the maximum server memory is set to 61440 MB.

When I look the Target server memory counter(SQl Server: Memory Manager) in perfmon, I am seeing 33287752 KB (maximum value). I was thinking the maximum value in the perfmon counter referenced here (Target server memory ) should be equivalent to maximum server memory set in server properties as Target server memory is the memory sql server can use. Is that not the case? Can
you please clarify? Thanks in advance.

Regards,
Adam

By: Ajmer Dhariwal

Ajmer Dhariwal — Mon, 26 Dec 2011 18:02:10 +0000

The max server memory limit defines the size of the buffer pool only.
Unfortunately, this does not and can not dictate SQL Server’s total memory usage.
The MemToLeave section of the post outlines where other processes and objects can use SQL Server’s memory, and therefore what to look out on your system to what might be contributing to the memory usage if it continues to increase.
If your memory usage increases beyond your max server memory limit added to your memtoleave (384 MB on a typical legacy x86 system) size then it’s reasonable to infer you have something leaking memory in SQL Server’s address space and take a look a those other processes mentioned that might be contributing to this. It’s also worth patching your SQL instance to make sure you’re on the latest SP level as it’s not unknown for some internal bugs to cause memory leak issues.

By: Joan

Joan — Thu, 22 Dec 2011 02:35:33 +0000

Refer to my post previously, we are using Windows Server 2003 Standard Edition SP2 with 4GB RAM and run SQL 2008 R2. I had set the sql server max server memory to 896MB on 15 Dec 2011.

The memory used for sqlservr.exe in task manager are listed below. It is increasing everyday and had exceeded the our setting of sql server max server memory already.
15 Dec 2011: 868,520KB (848MB)
22 Dec 2011: 950,148KB (927MB)

(1) Why it will exceed the limit even I had set the limit to 896MB?
(2) Will it use up all the available memory of server and lead to machine hanged? Or it will stop increasing up to a specific MB figure?
(3) Since the sql server is supporting a 7X24 system, so we cannot stop and restart sql service for reducing the memory used figure. Is there any long term solution can be provided for reducing the memory and keep it in a low figure?

Thanks for your help.

By: Ajmer Dhariwal

Ajmer Dhariwal — Tue, 06 Dec 2011 12:08:19 +0000

I’ve completely rewritten my answer (and withdrawn the previous responses to try and minimise any further confusion) as I’d made an incorrect assumption about awe on x64 systems (had to blow away a few cobwebs as it’s been a long time since I visited this particular area).

Whilst enabling AWE has no affect on x64 SQL Server, your x86 version of SQL Server should work much the same as it would on a 32-bit OS so you will be able to address more memory than the 4GB (default) limit you are coming up against by enabling awe.

So, sorry for confusing the matter, but if you just enable awe and cap the memory (and keep an eye on available memory you should be good to go.

If you’re still having issues, email me the sp_configure output (with ‘show advanced options’ enabled and the DBCC MEMORYSTATUS output).

By: Robert Hanson

Robert Hanson — Mon, 05 Dec 2011 19:53:11 +0000

Hello and thanks for your article. It is a good write up.
Please give me advice on my situation.

I am running 2008 enterprise x64 with 64GB ram. My sql server is 2005 enterprise x86.
The most ram that I can get the process to use is about 3.5GB.

Is there any modifications that can be done to force it to use more memory?
Thanks for your help, I much appreciate it.

Robert