VMWare store I/O control (SIOC)

Recently I’ve been seen several posts about storage control and I decided to understand where it’s coming from:

As far as I could understand it started back in 2009 during VMworld, one of the articles was about it. Click here to see

Then on June 2010, VMWARE released a video showing how it should works. (see it bellow)

How it works:
- It’s enable per Datastore
- You should set shares per VMs
- You can define IOPs limits per VMs

So, the host monitors it’s latency with the datastore when it reaches it’s limit all the VMs accessing it are prioritized according with it’s shares, just like CPU/Memory constrains, then each VM will have it’s share to access the storage, avoiding one VM to monopolizes the storage and kill the performance for every other VM.


Well, let’s be honest, it’s a very cool thing… I don’t know you guys, but by internal security policies we must run an antivirus scan once a week, it’s killing my VM’s.
A Bunch of VMs scanning a shared storage at the same time makes a lot of latency on the I/O and drops the performance on the storage aggressively. We tried to split the scan schedule across other days and times, which helped us a little bit, but did not solve the whole problem.

VMware is saying it should be available on VSphere 4.1 release. Let’s see…