We are in the process of upgrading our production environment to vSphere 5.0 U1. A new vCenter 5.0 server is already in place, and we attached the production ESXi hosts (that are still on 4.1 U2) to it.
The next step would be to upgrade the hosts. In the meantime, since this is a qualified production environment running more than 1.500 virtual servers I became a bit paranoid about hardware and software/firmware compatibility, and decided to double check if the environment is fully supported (or if we should upgrade any firmware first). I was pretty confident that we are on the safe side because we never had any issues with vSphere 4.1 and always kept the environment up to date.
But then I stumbled over this VMware KB article: EMC CX and VNX Firmware and ESX requirements for vStorage APIs for Array Integration (VAAI) support. It states that ESXi 5.0 does not support VAAI on our Clariion CX4 arrays even although they have the latest FLARE code:
|vSphere 4.1||vSphere 5.0|
|CX4 Series Flare 30/29/28+||VAAI Supported||Not Supported|
|VNX Series OE 31 or Later *||VAAI Supported||VAAI Supported|
I checked the test hosts that we already updated and they showed VAAI being supported on the CX4 LUNs in the vSphere client. However, the KB article recommends to disable VAAI on these hosts ...
I quickly searched the Internet for relevant posts and statements and browsed through the VMware Community forums. There I found this thread where people complain about the VAAI status shown as unsupported. It looks like there are dependencies to the LUN size (smaller or larger than 2TB) and to the array's failover mode (sounds like you need to use ALUA / failover mode = 4 which we are already using). But from this post I get the impression that everything is fixed with the latest 30.x FLARE code releases).
We contacted both VMware and EMC to get some clarification now, and I will keep this thread updated with any new information. In the meantime I ask everyone using ESXi 5.0 with EMC CX storage to comment on this post whether you are using VAAI, if you have any issues with it, and what FLARE code you have on the arrays. BTW, you can check what VAAI primitives are in use with your storage LUNs by running the following esxcli
esxcli storage core device vaai status get
Thanks in advance for any helpful comments!