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Tempdb : ONE Data File per cpu Expand / Collapse
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Posted Tuesday, September 11, 2012 12:57 AM
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Good Day,
w had an auditing team running Microsoft Assessment on our database servers . This product recommends that the principle of creating ONE datafile per cpu be
deployed on all the SQL Servers regardless of the load on the server . How can Microsoft release a product like this ?
Post #1357162
Posted Tuesday, September 11, 2012 1:21 AM


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The reality is, if you don't have the load then you dont need to it's more a best practice. This has been blogged many times by many different people.

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Posted Tuesday, September 11, 2012 2:15 AM
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lianvh (9/11/2012)
Good Day,
w had an auditing team running Microsoft Assessment on our database servers . This product recommends that the principle of creating ONE datafile per cpu be
deployed on all the SQL Servers regardless of the load on the server . How can Microsoft release a product like this ?


such advice had appeared from top consultants who work on very big and heavy farms. They suggested to improve the number of files per cpu only after analysing wait statistics and contention GAM and SGAM pages(can't recall exact terminology). We should be careful with what we choose. Read some whitepapers from SQLCAT team, PSSQL team, blogs from Paul Randal,Brent Ozar and analyse what they suggest before we make this implementation in our production servers.

Thanks
Chandan
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Posted Tuesday, September 11, 2012 2:28 AM
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The recommendation is per cpu core and it is also a microsoft recommendation.

http://msdn.microsoft.com/en-us/library/ms175527(v=sql.105).aspx

I'm not entirely sure what you mean by "How can Microsoft release a product like this"... Do you find the recommendation bad in some way? Do you have an objection to creating multiple data files?
Post #1357190
Posted Tuesday, September 11, 2012 2:42 AM


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http://www.sqlskills.com/BLOGS/PAUL/post/A-SQL-Server-DBA-myth-a-day-%281230%29-tempdb-should-always-have-one-data-file-per-processor-core.aspx



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Posted Tuesday, September 11, 2012 2:45 AM
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<sigh> were the auditors dbas?

thats a rather blanket recommendation, and there are lots of other recommendations than one file per core.

The recommendation should be that if you are not using multiple files for tempdb you investigate whether your system would benefit from doing so, as there is a chance it could do. Are you having any performance problems? A system that is not a heavy user of tempdb is unlikely to require it.


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Post #1357198
Posted Tuesday, September 11, 2012 2:48 AM
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I am frustrated, because , a consultancy firm used this tool and now to keep the peace we have to implement this setting.
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Posted Tuesday, September 11, 2012 3:11 AM
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read the blog from paul randal anthony posted and check out the scripts it links to which determine if you have tempdb contention. If you have no latch contention on tempdb allocation pages that is evidence you can present that multiple files will not be required.

If you are forced to do this it may not do any harm but point out it could be unnecessary and the server should be monitored after applying the changes.


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Posted Tuesday, September 11, 2012 4:28 AM


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The later recommendation is actually files equal to 1\4 - 1\2 the number of CPU cores

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Posted Wednesday, September 12, 2012 4:26 AM


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lianvh (9/11/2012)
I am frustrated, because , a consultancy firm used this tool and now to keep the peace we have to implement this setting.


May I recommend that you find a consultancy that is a) capable of independent thinking and which is up to date on current SQL Server "best practices" and more importantly b) recommends things that are necessary for YOUR ENVIRONMENT to function optimally/correctly and which shows you WHY they make such recommendations using metrics from YOUR system(s)?!?

I happen to know of just such a consultancy, btw.


Best,

Kevin G. Boles
SQL Server Consultant
SQL MVP 2007-2012
TheSQLGuru at GMail
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