cluster nodes
Ah, I see... But then again, you have more config options if you talk to one of Apple's business consultants and you can configure an Xserve with no drives if you'd like. Not sure what else the prior cluster node configurations had though, I guess I was unaware of their existence -- never saw them on the site, but I didn't really look.
I wasn't aware you could buy an XServe with no drives. It's odd for vendors to ship devices that can't be bench tested as is (unless Apple remote boots them on the line).
One of my big complaints with the XServe is that you don't get empty drive sleds if you don't order Apple drives. Apple ships covers for the un-used drives and you don't get the drive sleds unless you buy an expensive module from Apple.
Another complaint, Apple uses SMART but they don't support SMART on drives other than those that ship in XServes. The drives have to have Apple approved firmware. We bought 80GB modules and upgraded to nicer 300GB models (cheaper OEM even with a spare on the shelf compared to Apple's 250s) and the XServe won't read the SMART data from the drives.
The whole point of the XServe Cluster Node was to leave the frills out, like the drive bays and drives, so that you can get the most bang for the lowest buck. If Apple does go back to a cluster node, they'd likely drop the dual PowerSupplies also since a cluster node can go off line without pulling down a cluster.
A few bucks doesn't seem like much until you start pricing 40 or 100 or even 1000 compute nodes and then $300ish per machine becomes real money. I've got a group that has funds for a $300,000 cluster next year (and no money for additional IT ;-). Even if you dropped $250,000 on compute nodes and the rest on infrastructure you're looking at 50 nice compute nodes (at 5K apeace). Drop $300 per node and you've got another free $15,000. On a tight IT budget, that's a lot of money. Hell, my most metrics that's a lot of money.
I'm actually not looking to buy an Apple server for the small project I mentioned earlier. I need something with guaranteed Debian Linux support (or SuSe at the very least). I do want to go Core2Duo or Core2Quatro since we have tight thermal requirements and price/performance is a huge issue.