As we have discovered with worsening problems over the past 6 months, Apple has a very serious problem with their latest Mac Pro machines running the Intel "hartwell" chip on the ethernet ports. With bi-directional traffic to / from our ethernet based SAN, we can predict that our latest Mac Pro, the 2.93 Nehelam quad core machine, will disconnect from our SAN 8 times out of 10. The problem has been worsening and so far Apple has zero answers to the problem. Even Snow Leopard does not address this issue.
If you have any machine prior to the 2.93 Quad Core machine, you should be ok. We have three other Macs that all run on the SAN with no issues. It's only this machine and I have been told the problem is being repeated on other Mac Pros with this same "Hartwell" chip.
So if you're a heavy user of ethernet networking and especially looking at / using ethernet based SAN like we do, check with your networking folks before you purchase any new Mac Pros. To say we're disappointed with Apple right now is an understatement. Pay $6,000 for a new machine and find out it won't perform to the same specs as 2 and 3 year old computers.