Disconnect (Or Even Remove) Removable Devices
Here's a few facts about Windows (I don't know about Linux as I have not looked into the subject as much for it, but I suspect it to be similar) removable devices:
- Windows polls a local CDROM drive every 10 seconds
- Windows polls a local USB drive between every 1–20 milliseconds (see this article).
Now for a server farm with only a few dozen VMs, this isn't a big issue; but at scale it is a different story. Consider the following scenario:
- 500-guest Windows 7 VDI deployment
- Each with USB access and local CDROM drive access set to autoconnect
Additionally, many of us use ISO images for our servers; how many admins forget to disconnect the CDROM image when they are finished—more than that, how many forget to deconfigure the CDROM drive from the datastore path? Yes, a VM guest still configured to an ISO path will poll, as far as I know (if anyone knows for sure and has a link to VMware article, I would appreciate it). Don't forget, it can be very easy how to know if VM has a path configured to an ISO.
- Get rid of that floppy drive. Drop it like it's hot.
- Consider changing from an ISO datastore scheme to a file server repository scheme (especially for larger deployments); then you can leave out the CDROM as well.
- If you do #2, and you still need an ISO image, you can always connect it through the legacy (desktop) client.
- For VDI, really examine A) which users actually need USB access, and B) what your connection policy will be for that (autoconnect or manual). In some instances, such as in a military scenario, it is beneficial from a compute standpoint to have a "no USB devices" business policy which saves a lot of CPU cycles in VDI deployments.