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Possible Duplicate:
Hyper-V and Hyper-threading: On or off?
Can you help me with my software licensing issue?

I've seen lots of people saying we should turn hyperthreading on on hyper-v hosts, but I've got a dilemma.

We're going to be running SQL Server 2012 Enterprise on a 2012 hyper-V cluster. This is licenced per core, and in a virtual hyperthreaded environment I think that core is a thread, not a full core. It's also quite pricey compared to the hardware cost :-)

If our SQL Server instances start being CPU-bound, how much extra processing power would we get from 4 non-hyperthread cores vs 4 threads (ie equiv to 2 cores)?

Should I be considering running my hyper-v environment with hyperthreading turned off?

Community
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Clive George
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2 Answers2

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Look at licensing at the host level instead of the VM level. If your cost has 24 cores and you've got two hosts you'll need to license 48 cores. If your VMs total up to 60 vCPUs it'll be cheaper to license at the host level.

This requires that you have SA and an EA, but if you are buying this much software you'll want these anyway.

mrdenny
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For a comparable reason we're running our oracle server in a virtual machine BUT the host has only one socket, limited amount of memory and no access to the SAN. We have virtualized it mainly to be able to do snapshots and fast recovery and switchover to a new machine.

Oracles license management is insane... Every core wich can access the database server in a virtualized environment has to be paid. If we commected this server to our San we had to pay for all cores in the San capable of accessing the disc. So MS licensing cant be THAT bad...

cljk
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