What is the "cost" of a 8 vCPU VM?

[rfn]

Hi,

Because of a new SAN I have changed the way our Veeam Backup is configured. I'm now using a Windows Server 2008 R2 as a backup proxy on a production host because it has direct access to the fibre channel SAN. The proxy has 8 vCPU and 4 GB RAM and runs just fine and I have created a scheduled task that boots the VM a little while before the backup is starting and it shuts down some hours later.

Now I wish to replicate as well and maybe even several times a day for some VM's. This means that I either have to find a way to launch and shut down the proxy several times when it's need or just leave it running. And here's my real question:

Is there a "cost" to have this 8 vCPU VM idling on our hosts? Will it have an impact on performance when the host is busy or will it be negligible? The hosts are new IBM x3650 with two 6-core CPU's.

[Gostev]

There is certainly performance impact, but it is generally negligible if you have powerful modern hosts. Actually, I have shared the explanation to this in the weekly forum digest email couple of months ago, guess you are just not reading those - otherwise, you would not have this question

Here is the article > How too many vCPUs can negatively affect performance

[rfn]

I'm actually reading your very informative digest emails but I must have missed that link

Our hosts are not very busy, not the least, so I don't think that it will be a problem, but with replication running during day hours then that will of course change and that 8 vCPU VM could become a resource hog. I will have to watch it and monitor the READY and CO-STOP values to see if they increase from their current value.