Virginia Tech Upgrade: PowerMac G5 to Xserve G5

An anonymous reader writes "Virginia Tech officially announced that they will be migrating their G5 Supercomputer from PowerMac G5s to Xserves. According to the article, the Xserve G5s will reduce power consumption, heat production and decrease the system size by a factor of three. The pricing of the upgrade is still being determined, and according to Srinidhi Varadarajan, they are working on getting "very good homes" for the PowerMac G5s which will be replaced."

Comments

Speed Improvments

[beelsebob]

While providing no real speed improvement this should actually speed up the cluster by a factor two - The XServe G5s have error correcting RAM in which should stop them having to run jobs twice just to be sure of getting the right result. They may even get a slight speed boost from having a 1.1Ghz bus rather than a 1Ghz one.

Bob

Re:Speed Improvments

[Anonymous Coward]

ECC checking only adds a single clock cycle on reads and imposes no additional delays on writes since the ECC generation executes in parallel with other tasks. This delay only matters for the first cycle of a transaction; adding to the overall first access latency. The rest of the data transfers are pipelined so no additional delays are incurred. For well designed memory controllers(SDRAM,DDR) FAL is ~13+ base bus clocks for poorly designed ones ~17+ base bus clocks. 4-8% percent degredation in overall system performance is not likely(perhaps a single test can show this).

Re:Well duh?

[beelsebob]

I'm sure VirginiaTech realised that there would be 1U boxen along soon... What they also realised was that they had a tight deadline to get their computer tested for inclusion in the Top500 list - without the P3 rating they would have lost a LOT of jobs.

Bob

Re:The Cost?

[jocknerd]

They've already covered their costs in publicity and research. Getting on the Top500.org and being ranked #3 is huge. Well worth the $5 million they spent.

I know where they'll end up.

[blackchiney]

Trust me, the university is not letting anything out of their hands that can't be obsoleted first. It's a state school so they have a pecking order. My first bet is a large majority ends up at the Empo' followed by professors (who are also looking to build a smaller farm), faculty, staff, other state schools, and if we are so fortunate (and this is really a long shot) you can scoop one auctioned[PURCH].

Re:Instead of going 3x smaller

[aaarrrgggh]

Actually, the heat problem is a lot harder to deal with as you triple the density. They are looking at close to 12kW/rack, which pushes the envelope on what you can do with air.

For every five racks you need one computer A/C unit, without any redundancy. Anywhere you have a cable dam or piping, your ability to cool quickly goes to hell, even with a 24" raised floor.

I predict lots of problems with this upgrade... based on the marketing video they did with Apple. Just not set up to cool that kind of density.

Simple:

[daveschroeder]

Because the next list in June 2004, and the one after it, and the one after that, will include many new very, very expensive clusters (some $100M+) with performance far, far beyond 10Tflops.

So, yes, someone can build a 1101-G5 cluster right now, and be faster than VT's cluster. But they won't be on any list, and they definitely won't be anywhere near #3 on the next Top 500 list. And neither will VT.

That's why the whole VT #3 thing is the coup that it is: the timing was *perfect* for them to take the #3 spot for a mere $5.2M. The PR and grants they'll get *because of* that are more than worth it. That will never happen again for anywhere near that small an amount of money anytime soon.

See some of the new clusters that will be in the Top 10 on the next list:

http://www.bayarea.net/~kins/AboutMe/GIFs/TOP500_l ist_for_CPU.gif