IO limiting VM on VSAN

[AndreasBergman]

Last time i fiddled with VSAN, in September, i read somewhere that one cannot IO limit VMs that is running on VSAN. Is this correct? Or have I misinterpreted something?

[CHogan]

If by I/O limit, you mean Storage I/O Control, then yes, that is correct.

VSAN and SIOC are not designed to work together. In fact, you will see that SIOC cannot be enabled on the VSAN datastore.

[AndreasBergman]

Thanks, I was thinking about the IOPs limit available under resources in VM settings. I'm not sure if that setting is a part of SIOC? I know the shares value is.

Is there any other way to limit IOPS on a VM running on VSAN?

[vThinkBeyondVM]

Yes limit is not part of SIOC. SIOC throttles the LUN based on IOPS shares when there is IO contention.  IOPS limit set on the VMDK will be considered by the local host scheduler(aka SFQ) of the ESXi.

Refer: VMware KB: Limiting disk I/O from a specific virtual machine

I guess, we need to explore vSAN policy based management for more on limit on vSAN datastore .I will dig into the same & will come back

[acasanovanex]

Did anyone find any way of limiting IOPs for a VM residing on a VSAN datastore?!

[zdickinson]

I don't know about SIOC, but it appears as if you can still go into the resource tab of a VM and set share and IOPs limits.  Thank you, Zach.

[acasanovanex]

That is not true. At least for version 6.0.0. The UI section where I am supossed to configure limits is greyed out when the VM runs in a VSAN Datastore.

I can set a value through powercli, but it is ignored completely (It appears as applied if you look at the web interface, but IOPs are not limited).

[zdickinson]

Interesting, because I was in the VIC and it was not grayed out.  Have you tried the VIC and not the Web Client?  Thank you, Zach.

[acasanovanex]

Thanks zdickinson, the C# client allowed to modify the parameter. The problem is the config doesn't work anymore when the VM is residing in a vsan datastore. The limit didn't work either when we modified through set-vmresourceconfiguration powerCLI command.