http://www.gabesvirtualworld.com has a blog entry titled Prevent your LUNs running out of space
Don’t we all know the time you forgot to monitor your LUN available space? The call at 3am in the night from the monitoring-room that a LUN has no free space and VMs are crashing (VMs with active snapshots). So had we. We now have configured addequate monitoring to alert when less then 20Gb free space. But despite this it could still occure that a LUN runs out of space.
Some good stuff, check it out.
I like the fake data idea, but I would think that it would be a waste of space in a large environment, and what would happen if you where deduping?