What’s this? “Diskless VDI”, you say? BAH! Phooey! You’ve gone mad!
Well, maybe not.
It works like this: Take a server, load it with a metric tonne of RAM, and then import the ILIO virtual appliance. Go through the configuration wizard (literally takes about 4 minutes), and viola! You have just created an NFS export – OF RAM. Okay, okay, but how is that going to help, and what is actually going on?
After you import the virtual appliance, assign it an ungodly amount of RAM (the minimum is 26GB). Then configure a reservation so it ALWAYS has that amount of RAM. When you boot the appliance, it checks to see how much RAM it’s been given, subtracts some so it is able to function, and then creates a RAMDISK out of what’s left, and presents it back to the hypervisor as an NFS export. Not only does it allow you to have storage in RAM, but I know what you’re thinking.. “How is having a 20GB NFS export going to help me?” It probably wouldn’t, EXCEPT – The ILIO appliance also performs deduplication!
So.. You load up the appliance, follow the guide, configure the reservations for memory and processor, then attach the NFS export to the hypervisor host that it’s sitting on. What then? You provision your VDI VM’s INTO the NFS export. Then, you’re using RAM to run the VMs, so the performance is incredible! Altantis reports they had a customer perform independent benchmarking and they were able to get over 200 IOPS per VM! That’s all fine and dandy, but why would you ever need such speed? I’ll get to that. More importantly, think of the savings by doing it this way: Install the hypervisor onto the internal solid-state storage in a server (HPs come with SD card slots). Store your templates or golden images on some shared storage somewhere (an NFS export on a Windows server would be sufficient). We’ll assume you are using PVS here for simplicity’s sake. So your templates are on a windows NFS export. You go into PVS, run the XD wizard, and provision your VMs INTO the RAMDISK NFS export (you ARE using local disk cache in your VMs, aren’t you??). Now, you have all your VDI VMs running, literally with NO spinning disk in the server. This means you can use 1U servers, or blades, or whatever else you want, for the hypervisor, even if they can’t hold a bunch of disk! Further, you have no requirement for a SAN, AND you get blazing fast performance! The downside? Since the NFS export is nothing more than memory, it obviously won’t survive a reboot. This means every time you reboot the server, you need to go into PVS, XD, AD, and the hypervisor, and remove all the VMs that are provisioned into the RAMDISK on the host you want to reboot. But really.. How often do you reboot your hosts?
So you’re sitting there thinking “That’s great, but I already have all the disk. What is a possible use case for this?” How many times have you heard (or said) “We MUST run anti-virus software in our VDI VMs!” That will just wreck the performance of a VDI farm, or, at the very least, it will drive storage costs through the roof, right? Not anymore! You’ll have MORE than enough IOPS to run anti-virus in your VDI VMs! All for a retail cost of $110/seat (including maintenance)!
Want more info? http://www.atlantiscomputing.com/products/diskless-vdi/
Be sure to check out Brian Madden’s interview with them at VMWorld, where they won the Best of VMWorld 2012 in the Desktop Virtualization category: http://www.brianmadden.com/blogs/videos/archive/2012/09/10/vmworld-2012-atlantis-computing.aspx