February 24, 2015 at 3:36 am
We currently have 16 processors on a 2008 box.
We will soon be upgrading to 2014.
My manager believes we are underutilising the processors we have and that we should buy less for the 2014 box.
I have run a number of counters for a couple of weeks and it confirms there are no CPU pressures. (ie % Processor Time is consistently less than 20% and Processor Queue Length is generally 2 or less).
How can I now identify the number of CPUs we can safely buy for the new box without affecting performance?
Kind regards,
George
February 24, 2015 at 4:26 am
I wouldn't say that's a precise art. You do know how much you're utilizing your current system. You can extrapolate somewhat from there. But, you also need to look at your max degree of parallelism and your cost threshold for parallelism. I'd also check to see if you have affinity set for any processors. All that can help you figure out what you're likely to see if you reduce the number of processors available on the system.
I wouldn't recommend going too low, but it does sound like 16 is too big. What about just continuing to use that system, but virtualize, put two or three SQL Server instances on it?
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning
February 24, 2015 at 4:46 am
Hi Grant,
Thank you very much for your reply. We are considering virtualization too, so that sounds like a good idea.
We do have affinity set for the processors, but I have not checked the max degree of parallelism and the cost threshold for parallelism yet.
I will look into these shortly.
Kind regards,
George
February 24, 2015 at 5:41 am
Depending on what you have for affinity, that may be limiting the number of processors being used and will give you a baseline to start from.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning
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