Thoughts and opinions...dual and quad vCPU VMs

[CiscoKid]

I am looking for feedback from anyone willing to comment on this subject and would like to make some easy points here :^0. I want to hear of success stories from administrators who have decided to implement dual/quad vCPU VMs in their environment. On the flip side, I also want to hear of disaster stories from administrators whose environments were severely impacted as a result of employing dual/quad vCPU VMs. In both cases, please provide the targeted application and the operating system that their VMs were running that sparked the desicion to use dual/quad vCPUs. Thanks in advance.

[Rodos]

Well anything for points

Its not really a huge thing. Our general policy is to give everything a single vCPU unless our review of the application load and guest OS reveal it warrants the additional vCPU. Have not needed to do four vCPU yet. Exchange and SQL under Windows use two vCPU very effectively and produce great results.

Have seen severe impacts where most machines VMs were two vCPU and all the pCPUs in the hosts were only dual core. Scheduling fell over itself and performance was low. The machines did not need two vCPU, it was left over from the P2V process.

Hope that helps.

Considering awarding points if this is of use

[mcowger]

We have about 113 VMs. 50 or so of which are 4vCPU machines running oracle+java automated tests in redhat EL4. They run fine (we have dual socket machines with 8 cores total). another 10 or so are 4 vCPU windows boxes running SQL server and exchange. They all run fine (and yes, they are all all fully multithreaded tests which max out all 4 CPUs).

--Matt

[CiscoKid]

Thanks for participating...keep them coming. I am sure that others will benefit from this thread.

[BigHug]

Hi, Matt:

How many 4-vcpu vms do you run on the 8-core host? And how many other 1-vcpu or 2-vcpu vms do you run with the 4-vcpu vm on 1 8-core host? We have been requested to run 4-vcpu vms on our 8-core hosts. However, we found out the overheads are quite large. Maybe it's better off to run them on physical servers.

Thanks,

[mcowger]

Hi,

I'm not sure exactly, as we tend to let DRS move VMs around at will, so it varies. Usually its 1 or 2 4-core VMs on a host and a handful of single core VMs.

--Matt