Running VMware 6.0? slow performance on W2k12 and SQL server? you need to check this!

[ranj]

Hi All

 

Just a heads up to anyone not running a recent release of VMware vSphere 6.

 

If you see any performance issues with your Windows 2012 servers using hardware version 11 and the VMXNET3 virtual adapter and the server relies on a SQL server for database access your most likely suffering an issue which we been seeing in our environment recently.

 

Vmware have released a KB article, if your running ESXi 6.0 update 2 or above you should be fine but anyone running releases before this may need to following this KB article:

 

https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2129176

 

Symptoms are:

 

•You notice performance degradation for some client/servers workloads.

•Packets have up to a 0.5 second delay over the expected arrival in the application.

 

This issue is observed under these conditions:

 

◦The guest operating system is Windows Server 2012, Windows 8 or later.

◦The virtual machine is on hardware version 11/ ESXi 6.0 compatibility.

◦The virtual NIC is vmxnet3 and the driver version is 1.6.6.0.

◦The Receive Side Coalescing (RSC) feature is enabled globally and on the vmxnet3 adapter.

◦This issue is more prevalent when:

 

◾Running Microsoft SQL/TDS based workloads

◾Using Jumbo Frames

◾The client and server are on two different hosts

 

Hope it helps anyone suffering these issues as this did take us a while to figure out what was going!