There was a part of me that wanted to hate on Instant Clones that are new in Horizon 7 but the fact is they’re worth the price of admission. Instant-clones has very low overhead to provide true on-demand desktops or as VMware is tagging it, Just-In-Time desktops.In my health care days the non-president desktops and shift change always resulted it some blunt force trauma around 7 am and 7 pm when staff would start their day. They only real way to counter balance the added load of login storms was to make sure the desktops were pre-built. This of course means you need so have some desktops sitting around doing nothing waiting for the these two time periods in the day, or use generic logins and then the user never disconnects which was another bag of problems.
Instant-clones ability to clone a live running VM by simply quiescing the VM is really amazing. Have you ever changed the name of the a desktop and then windows tells you to reboot? If your like me your try to do 5 or 6 other things before you have to reboot which usually ends up in a mess. Instant-clones uses a feature called clone prep to add the VM to AD and change it’s name, all while not having to reboot the VM. When you see a power on operation inside of vCenter it’s actually just quiescing the desktop so there is very low overhead.
When I went to test instant-clones I wanted to see if on-demand desktops was actually possible without destroying node densities. I had two test runs with Login VSI, 1 run with 400 knowledge users with all the desktops pre-deployed and 1 run with 400 knowledge users but I only started with 50 desktops. I had set the desktop pool to always have at least 30 free desktops until the pool got to 400 desktops.
The darker blue line represents the on-demand test and you can see that the impact over 400 hundred users is pretty small. This is pretty remarkable from a CPU and memory consumption on boot that is being almost eliminated.
It’s not all unicorns and rainbows however, instant clones does have some limitations in the first release:
No dedicated Desktop Pools
No RDS Desktop or Application Pools
Limited SVGA Support – Fixed max resolution & number of monitors
No 3D Rendering / GPU Support
No Sysprep support – Single SID across pool
No VVOL or VAAI NFS Hardware Clones support (Smaller desktops pools may take longer to provision)
No Multi-VLAN Support in a single Pool
No Reusable Computer Accounts
No Persistent Disks – Use Writable Volumes \ Flex App \ Unidesk \ RES …….
vMotion Is supported
Like anything use case will dictate when this gets used but its a powerful tool inside of Horizon. I plan to show some of the differences between View Composer and Instant Clones in my next posts. Also keep in mind that you still need high IO to service your desktops. Size for the peaks or face the wrath of your end users.