Storage IO Control

[daunce]

Is SOIC something that should be enabled by default?

Can it have any negative affects?

We have 2 clusters of 5 hosts each attached to FC SAN for each cluster.

The SAN also has many other non-esx physical boxes that use it. Every now and then, a physical box goes off the rails, and impacts every LUN using that same controller. Only then are changes made to the HBA on the physical box.

It's yet to be a VM causing the issue. But i guess one day it could. So i've been looking into the down side of it.

Any good/bad experiences with it?

Thanks.

[chriswahl · Accepted solution]

I wouldn't say it should be on by default. If you're not going to use it and keep all disk shares equal then there's a good arguement to not turn it on. It only kicks in when there is contention for the storage resource, so if you have one VM go "crazy" with I/O and the other VMs are dormant, it's still going to crush that LUN.

I've got it on for a few FC LUNs on a non-prod cluster to give a disk hungry VM a leg up over some other servers. It works pretty well at making sure that when that VM needs disk I/O it's given priority. No downsides I can think of. Be careful about going hardcore with share values; simple is usually better.

This might also be a good read for you:

http://www.vmware.com/files/pdf/techpaper/vsp_41_perf_SIOC.pdf

Cheers.

[daunce]

I've got it on for a few FC LUNs on a non-prod cluster to give a disk hungry VM a leg up over some other servers.

Thanks for the reply..

Why not do it across the board? Or are you also testing it to start with?

[admin]

I found a very useful document on Storage IO Control which explains how to configure SIOC, how it works, prons, cons etc. Refer to http://www.vmware.com/files/pdf/techpaper/VMW-vSphere41-SIOC.pdf which may help you to clarify your queries.

~Sudhish

[chriswahl]

Prod uses NFS, which doesn't support SIOC.

[daunce]

The only downside to SIOC i found is for tiered storage when the SAN will move the datastore to a different tier, but we dont have anything that fancy.

Thanks everyone for all your comments.

I've put in the change request!