July 12, 2011 at 9:58 pm
Comments posted to this topic are about the item Controlling I/O
July 12, 2011 at 11:49 pm
Nice question, thanks!
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July 13, 2011 at 4:02 am
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July 13, 2011 at 4:03 am
Always great learning something from QoD - Thanks
July 13, 2011 at 5:24 am
Good question, thanks.
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July 13, 2011 at 5:55 am
Somehow I knew I was going to get this wrong and I was wrong indeed. However, this is why:
http://msdn.microsoft.com/en-us/library/ms189629.aspx
States, "Affinity support for servers with 33 to 64 processors is only available on 64-bit operating systems." means that you can use it for up to 64 processors.
Also, "To cover more than 32 CPUs, configure a four-byte affinity I/O mask for the first 32 CPUs and up to a four-byte affinity64 I/O mask for the remaining CPUs."
The explanation said, "Note that you do not want to assign processing tasks to the same CPUs that handle I/O, so in using this affinity, you would assign affinity for processing to some CPUs and I/O to others." but this doesn't mean you cannot do it.
Summary, I still believe the 1-64 CPU option is the correct one according to Microsoft.
July 13, 2011 at 6:22 am
cengland0 (7/13/2011)
Somehow I knew I was going to get this wrong and I was wrong indeed. However, this is why:http://msdn.microsoft.com/en-us/library/ms189629.aspx
States, "Affinity support for servers with 33 to 64 processors is only available on 64-bit operating systems." means that you can use it for up to 64 processors.
Also, "To cover more than 32 CPUs, configure a four-byte affinity I/O mask for the first 32 CPUs and up to a four-byte affinity64 I/O mask for the remaining CPUs."
The explanation said, "Note that you do not want to assign processing tasks to the same CPUs that handle I/O, so in using this affinity, you would assign affinity for processing to some CPUs and I/O to others." but this doesn't mean you cannot do it.
Summary, I still believe the 1-64 CPU option is the correct one according to Microsoft.
I understand your point, but the affinity I/O mask on it's own can only handle 32 CPUs. If you want more, you need the help of the additional affinity64 I/O mask.
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July 13, 2011 at 6:47 am
Good question....I learned something today.
July 13, 2011 at 7:19 am
Great question and i got it wrong because i never used it. Learn something new everyday.
July 13, 2011 at 7:35 am
I also got this wrong because I chose 1 -64 processors. This argument/discussion can go either way really. More importantly this feature is deprecated according to BOL. Good question about a feature I was unaware of.
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July 13, 2011 at 8:44 am
Good question and explanation. Thanks!
July 13, 2011 at 11:19 am
Nice question. I almost answered 1-64 but then read that there was a different option for affinity64 I/O. Had my fingers crossed answering this one.
July 13, 2011 at 12:24 pm
Woohoo, I remembered something from my MCITP studies.
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July 13, 2011 at 7:21 pm
Sean Lange (7/13/2011)
I also got this wrong because I chose 1 -64 processors. This argument/discussion can go either way really.
I think making a distinction between affinity I/O mask and affinity64 I/O mask rates quite low on the QotD-sneak-o-meter. The question specified affinity I/O mask, and that does indeed only affect 32 CPU logical processors.
More importantly this feature is deprecated according to BOL. Good question about a feature I was unaware of.
Ah, no. You are confusing the (vastly more useful) affinity mask with affinity I/O mask. They do separate things, and only affinity mask is deprecated in favour of ALTER SERVER CONFIGURATION SET PROCESS AFFINITY. There is no corresponding replacement for affinity I/O mask or affinity64 I/O mask. Full set of BOL links:
All that said, it is extremely rare to set I/O mask at all, and even rarer to do it with good reason.
http://blogs.msdn.com/b/psssql/archive/2010/11/19/how-it-works-io-affinity-mask-should-i-use-it.aspx
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