Live editing/tuning disk IOPS limits?

[Yenya (Jan "Yenya" Kasprzak)]

Hi all,

is it possible to tune parameters of a running VM, in particular DISK/WRITE_IOPS_SEC? I tried to update the VM template in Sunstone (VM →Conf →Update Configuration →Advanced, and then adding WRITE_IOPS_SEC = "50" to the DISK = [ ... ] section), but as long as I save the template, it remains unchanged.

This is probably related to this old thread:

Manage IOPs Limit for VMs

Hello, I’m running into trouble limiting the drive speed of the VMs. At the moment there are several VMs installed with no IOPs limit configured. Is there a possibility to set a global Limit to make sure that the VMs are running, on let`s say a maximum of 500 IOPs per VM? I have tried to change the Template, deattached the current storage from the VM, created a new VM with the new Template and attached the old Storage to the VM. After i have attached the old Storage the Limit is gone and th…

Thanks,

-Yenya

[pczerny (Pavel Czerny)]

Unfortunately, there is no option to update VM disk attributes, not even for powered-off VMs. The best you can do is detach the disk and attach it again with new attributes.

[DeBuXer]

If you want to do this live, it must be done on the hypervisor where the instance is running. With libvirt, you can do it as follows:

Show which targets the instance has:

virsh domblklist one-<id>

Show the current settings of the target:

virsh blkdeviotune one-<id> vdX
or
virsh blkdeviotune one-<id> sdX

Update the settings live:

virsh blkdeviotune one-<id> sdX --live --write-iops-sec <value>

And don’t forget to modify the instance with onedb afterward, so that the settings are not lost when you power off and power on the instance.

onedb update-body vm --id <id>

<WRITE_IOPS_SEC><![CDATA[<value>]]></WRITE_IOPS_SEC>