VM ESX hosts have hyperthreaded cores enabled on database server.

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Bugmesh asked Mar 31, '14

VM ESX hosts have hyperthreaded cores enabled on database server.

I have been looking into the wait times on our database servers and was curious about how/if the ESX hosts that support our database could be causing some issues with MAXDOP currently set to '0'. I know in a physical server environment you would probably want to have hyperthreading turned off. Is it the same with a Virual Machine? Should the ESX hosts supporting the VM have hyperthreading turned off? I would appreciate any assistance provided Thank You

server maxdop vm hyperthreading

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Answer 1 · 2014-04-01T11:24:46Z

Kev Riley answered Apr 1, '14

This isn't going to answer your specific VM question, but I just wanted to challenge your view about hyperthreading on physical servers. It used to be the case that for 'older' processors, it was recommended that HT be turned off. However since the introduction of the Nehalem processors in 2010, it's no longer such a broad sweep of advice. OLTP benefits more than OLAP/datawarehousing, but as ever, 'it depends' and 'your mileage may vary'.

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sp_lock commented · Apr 01, 2014 at 01:48 PM

+1. You also find some vendors tell you the best practice in terms of MAXDOP. MS CRM and Sharepoint are a perfect example.

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ThomasRushton ♦♦ commented · Apr 01, 2014 at 09:24 PM

@sp-lock yup. Both those are recommended to have MAXDOP of 1, which will kill your server for any larger queries. Plus those systems will get you to use their own maintenance routines, rather than the standard ones. My advice for those two systems is to keep them on their own separate boxes, away from anything else. But we're getting away from the main topic...

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