I've got one sitting around. Interesting thing: The cpu is a E6800 or so. You can literally shove a Q6600 in place if you run an OS that can microcode patch. 8gb of ECC max is weak.
Our main problem was the thermal shutdown and the P400 battery cable was too long should be a short one.
I have running with a $199 P812/1gbFBWC (P410 works great too, or LSI M5014 (cachecade!).
If you stare at the modules for the MSA60 and MSA2312 you'll see how the parts all come together.
Warning: The thermal envelope is heavy with this unit. I have 12 146gb 3.5" drives in the model that is rotting - When in use, it will run real hot since it wasn't meant to be a server. DISABLE THERMAL SHUTDOWN. About 100F the whole machine went into thermal shutdown - while my G4/G5/G6/G7 were happy. I think it's a bios bug that set the thermal cutoff way too low. 100F is hot, but it can take it.
Great little box, it was replaced by the DL180 G6 (sucks), and then the DL380 G6 as the choice for storage server. I'd be very surprised if you don't find a windows 2003 storage server key on the lid
remember the F8 raid util - don't use it. Use the HP SPP ACU utility, that way you can say drive 1-12 -> first raid-10, then drive 1-12-> next bit raid-5 , then drive 1-12 -> last bit raid-0, the F8 utility to setup raid will assume to make a raid set of out ## drives. IE first raid set drives 1-2 raid-10, next raid set drives 3-6 raid-5, last set raid 0. This is not nearly as well performing as one big set of drives (like how intel ICH does it).
Any questions ask - i've been using these for massive D2D shares for about 6 years. All servers and 60+ desktops do a nightly full compressed backup 7 days a weak to the poor gal. After the warranty gave up, we pulled the 500gb drives out and 1 dead, 3 near imminent but not (many bad sectors), and the rest were good. It was kind of odd since the bad ones were all on one side. Almost like it was torqued or racked improperly.
The reason I did the P812/P410 was esxi 5 doesn't like the P400 (LSI1078) with large partitions, while the PMC-adaptec P812/P410 could present the entire 12*2TB lun to esxi 5. Ever since the upgrade i've been running this guy in a VM (2008R2), and also running vcenter in a VM. It has enough mojo to do both and then some.