High CPU load on guest VM during backup.

[msolovey]

Hi!
We are using Veeam Backup 6.5
One of our VM's has normally 70%-80% CPU load and Network load. During the backup we noticed, that VM becomes unavailable because of CPU load is 100%. It is impossible to connect to server.
Does veeam backup effect on CPU load of VM?
Tnx

[veremin]

Hi Mikhail, is there anything specific about this VM? Does it host proxy role by any chance? Thanks.

[Gostev]

There is no sense in guessing here. Simply open a Task Manager inside the VM, and see which processes take most CPU (sort processes by CPU usage), and make a screenshot. Then start the backup job, wait for CPU to go to 100%, and make the same screenshot again. Then, compare the two screenshots side by side.

[msolovey]

It hosts SQL server database.
My question is more about theory. Theoretically, can veeam backup effects on CPU? Or it is just coincidence?

[veremin]

Yes, in case the VM runs some Veeam components, such as backup proxy.

[scott.anderson]

Also if your job is backup up of a Windows VM with application aware processing enabled the job will request that the OS performs a VSS snapshot. The VSS process will generate some VM level CPU and memory utilisation.
For large SQL and Exchange VM's this could be quite a bit of process!

[tsightler]

Also, assuming this VM has mulitple vCPUs and is doing a reasonable about of I/O, CPU usage within the guest will show as significantly increased due primarily to scheduling overhead of the host. This exhibits itself as high CPU usage in the guest, and high co-stop if monitored from a host perspective. You can read more about this specific phenomenon in VMware KB atricle 2000058. I don't know for sure if this is your issue, but I've seen it a few times on VMs with fairly heavy I/O and generally high CPU usage to begin with so I thought it was worth mentioning.

[martin.minne]

Hello,

Sorry for the reply on an old post, but i have a similar problem. I have a job which backup 4 VM.
On 3 VM we have performance issue when the job start: hight load,VM performances are terribly decreased. There is no veeam component installed on those VM, only guestos indexing is enabled for the entire job.

How is it possible?
Thank

[foggy]

Martin, which processes take CPU resources on those VMs during backup? What kind of applications are installed inside?