VM-FEX for VDI is Bogus

I had wriiten a post, #VDI Tip 69: Use QofS – UCS and VMware View 5 but it’s misleading. The premise of using QofS is still a good and should be done. Since VM-FEX is dependent on the number of PCI-devices that your server can handle. Since you can only have 32 PCI-devices per server and some are taken up my various functions, the Max is really 30 desktops. The report mentions 30 desktops being used for testing but never declared it as a limiting factor. I declare this report as Bogus!

If you want to run QofS with VDI you will need a Nexus 1000v or use the virtual distributed switch(vDS) and run the QofS from the vDS. If your running VDI with 30 VM’s or less per server, you work for a hardware vendor 🙂


#VDI Tip 64: Follow the Network Checklist

Funny thing about Virtual Desktop Infrastructure, it usually relies heavily on the network. Most of my last two days has been spent troubling shooting dropped PCoIP packets, so I feel it’s timely to make sure you have your basis covered.

So here is the big tip of the day, Read and follow this check list – PCoIP Virtual Desktop Network Design Checklist

Networking isn’t my strongest skill but luckily I work with some really smart people. I think the biggest take away from the checklist is WRED.(Weighted Random Early Detection). It provides preferential traffic handling for packets with higher priority. It can selectively discard lower priority traffic when the interface begins to get congested. Try to get your PCoIP traffic prioritized just under VoIP traffic. The above document notes ” Do not configure WRED on the physical interface as it will override all other QoS policies”. Most traffic monitoring tools are not granularity enough to catch the spikes in traffic. In the land PCoIP, 1 minute intervals does not pass the test.

If you have access to your Cisco Router, you can check for drop packets by using the CEF (Cisco Express Forwarding) commands.
show cef drop
show ip cef switching statistics

You can also check for high CPU utilization. Sometimes high CPU utilization will cause buffering. Buffering = BAD

Run something different than Cisco? Please comment and leave commands for other vendors.