I’m curious about all of those EQL users out there, do you use the web GUI for your firmware upgrades or do you use the CLI?
After reading the post below I think I’m leaning towards the CLI upgrade, you?
http://www.interweb.org.uk/2012/01/06/equallogic-kernel-panic-on-a-netbsd-processor/
During the upgrade I recieved a Kernel Panic and subsequent Panic Recovery, looks like the controller crashed during the update this resulted in the iSCSI targets being unavailable for a couple of minutes, the controllers did not fail over and I now have a Firmware mismatch.
Spoke to EqualLogic support, according to them there is a rare issue with FW Versions 5.1.x that in when you process a firmware update using the Java based Group Manager GUI, there are instances when the firmware file becomes corrupted. Support siad that this is a very rare issue and that it will be addressed in further updates.
Michael Ellerbeck 
Hi Michael, I’ve been updating Firmwares trough the web Gui since I started implementing this product with our customers.
I’ve never had an issue.
Then again, It’s indeed only a small step to FTP the file to the EQL and run the update trough the cli.
I might consider this for future 5.1.x upgrades.
Better safe then sorry 🙂
grts & best wishes
Patrick