Rackable still impressive.
"....and a few other tier-one server makers that have only nominal market share in blades (you know who you are, Sun Microsystems, Fujitsu-Siemens, Hitachi, and NEC)...." Oh dear, the Sunshiners are going to take you off their Christmas card lists for that!
".....The fact is, if IBM and HP blade customers want to add a reasonable amount of storage to their blades, they have to rip out about half the blades in the boxes and buy storage modules that link to the blades....." Hmmm, but if you have a lot of blades in one datacenter then you're also likely to have a SAN, and HP and IBM (and Dell) are all better placed with storage offerings and SAN switch interconnects than Rackable. Even without the SAN, HP can offer storage blades and even NAS appliance blades inside the chassis, which with Rackable are either not an option or the customer has to build after delivery.
Still, Rackable still make very good kit, and it's beacuse they have innovated new designs that meet evolving customer requirements that they have not just survived but prospered (someone may want to point this out to a certain Mr Schwartz....).
Quote: The wonder is that more companies don't make rack servers like this.
Nope: http://www.icp-epia.co.uk/index.php?act=viewCat&catId=91 Fits any mini-itx motherboard. It does not have the fancy features of rackable, but it allows similar densities when used with any of the mini-itx MBs out there. It is also dirt cheap. You can fit these back-to-back in any 19" rack.
I think the market needs both approaches
and both approaches can be implemented in good or bad ways. It really all comes down to budgets, time to deliver working systems and the integration of an organisation's server & LAN/SAN teams.
For my company the ability to pre-fill racks with relatively-cheap empty blade chassis, power them up, run the very few LAN/FC cables required back to the central switches, pre-config the switches and slam in blades as they're needed/delivered outweighs the 'cable-as-you-go' approach that I believe Rackable kit generally uses. This is obviously because there's a lot of latency in my company between the server and LAN/SAN teams and this isn't a problem at smaller or more integrated companies.
Also, and I'm happy to be wrong here, I'm pretty sure you can get more blades into the same space than rackable (HP C-class=160 servers/1920 cores in a 50U rack, Rackable=100/1200 cores).