One of the things that we hear most often is that it’s hard to identify the problem being the application, server, or network.  We can now officially add to this list: Application, server, network, or virtualization layer. 

Virtualization is to IT sorta what light is to physics.  Is it a wave?  A particle?  Is it a software thing?  Is it hardware?  Virtualization is… virtualization.  It’s something different, something new, and something which is very very difficult.  Also like physics.

And when things go wrong with virtualization, they can go wrong very very badly. According to Network World:

Many VMware customers Tuesday were prevented from logging onto their virtual servers as a bug distributed in a software update effectively stopped the boxes from powering up….

"This certainly appears to be the most publicized bug for VMware so far, and I think it is damaging to VMware and virtualization as a whole. The hypervisor is the lowest software level on the server and if you have an issue like this, boom, all your infrastructure is down," says Gary Chen, a senior analyst with Yankee Group. "Software will always have bugs, but a widespread issue like this that affects all VMs is really damaging, especially at this point in time where virtualization is starting to take off. VMware is going to have to fix this fast, provide an explanation, and outline what they will do to strengthen their QA in the future."

The bug is preventing users from powering on virtual machines, though VMs already running continue to do so.  There is a workaround – set the date back, turn on the VM, reset the date – but that can be tricky when certain applications need accurate timing information  – banking records, for instance.

Of course the fact that it’s complicated means that it’s even harder for lay people to understand. I’ll bet you that even though the real problem is the virtualization layer, end-users who find this problem prevents them from working blame the network.