Lync 2013/Skype for Business & Virtual Cores

Spotted an oddity on performance on some Skype for Business deployments….Around virtual cores.

I've been setting up a couple of Standard Edition servers recently, and I wasn't seeing the performance I expected when importing a fairly large number of users (about 3k) - this was a test lab. It was a bit confusing really, as the servers themselves were very well specified. 8 cores, 32Gb RAM, running on SSDs….albeit the platform being virtualised.

After playing around with it for a while, I could see that SQL Express only seemed to be executing on a single core, not up to 4 which is what I thought was standard. I.e. SQL Express can use up to four cores. You can see the restrictions in this article here:

Compute Capacity Limits by Edition of SQL Server

2012 version here).

In particular, pay attention to this bit:


It's limited to the less of 1 socket or 4 cores. So, having looked, my VMs were running not with a single socket with 8 cores, but as a server with 8 sockets, each with 1 core. Explained the restriction. Having spoken to the VMWare administrator, this got fixed pretty quickly. Haven't really looked at how, but there's a great article here explaining how to allocate cores per processor. As a side note, the memory is still limited to 1Gb for SQLe I believe.

Setting the number of cores per CPU in a virtual machine

Anyways, an interesting one, and something to watch out for.
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