Details spill on IBM's big iron Power7 servers

With Big Blue getting ready to launch its biggest Power7-based server, the 256-core Power 795 machine, on August 17 and four entry Power7 machines as well, resellers have been briefed and tongues have started wagging.

The Power 795 is a 256-core, 1,024-thread behemoth that will, as El Reg suggested, sport 8TB of main memory for those cores to play in. Sources familiar with IBM's plans say that this big, bad box will have two modes, just like the multi-chassis Power 780 server that was announced back in February.

That Power 780 machine scaled up to four interlinked chassis and scaling up to 64 cores running at 3.8GHz in MaxCore mode. If customers wanted more clock speeds, more cache, and more memory per core on this system, they can change a system setting and reboot the Power 780 into TurboCore mode, which only turns on half of the cores, but they run at 4.14GHz.

Sources tell El Reg that IBM will be putting a TurboCore mode on the Power 795, which means 128 of the cores are turned off, but the clock speeds will go up and the cache and main memory that can be allocated to each core doubles.

The basic design of the Power 795 will not change much from the existing Power6-based Power 595 server, which puts eight processor books - modular system boards with main memory slots - in a single system image.

What is the case is that each processor socket now holds eight Power7 cores instead of two Power6 cores. At the time of writing, it is unclear what the clock speeds will be inside the Power 795 machine, but they will almost certainly be lower than the 5GHz speed of the Power6 processors used in the Power 595 and higher than the same as or higher than 3.8GHz and 4.14GHz parts used in the Power 780.

Because the Power 795 takes up an entire rack instead of cramming processors into a 4U rack chassis, they can run a little hotter because there is more airflow over them.

It would not be surprising to see IBM also create a spinoff of the Power 795, perhaps called the Power 790, that uses six-core Power7 semi-dud chips and that does not include the TurboCore mode. The multi-chassis Power 770 server announced in February used a mix of six-core or eight-core Power7 chips running at 3.1GHz and 3.5GHz and did not have the TurboCore mode. It also carried a lower price than the Power 780. If IBM wants to make the most use of all the chips coming off its fab in East Fishkill, New York, it needs to do something like this.

We had already head that the four entry rack and tower Power7 machines would be called the Power 710, 720, 730, and 740. The 710 and 730 are 2U rack servers, sources tell El Reg, while the Power 720 and 740 are 4U boxes like the existing Power 750 - and the individual nodes in the multi-chassis Power 770 and 780 machines.

The Power 720, 740, and 750 machines come in either rack or tower versions. It looks like the Power 710 and 720 will have a single processor card with a single socket, while the Power 730 and 740 will offer two sockets.

IBM is expected to use semi-dud versions of its Power7 chips in these machines, with four or eight cores, as well as fully capable eight-core versions.

The exact processing speed and L3 cache sizes of the processors used in these four itty bitty Power7 boxes is not known, but it is a fair guess that some of them will be slow with comparatively low prices.

There is some murmuring that the Power 710 and 730 servers will have faster processors than the Power 720 and 740 servers, which may seem odd given that the Power 710 and 730 machines are smaller boxes. But perhaps IBM has a newfound interest in competing for low-end infrastructure workloads, displacing older Sun and Hewlett-Packard iron. Or maybe customers are balking at the high prices IBM is charging for Power7 capacity and looking at x64 alternatives.

Wicked core price

On the existing Power 750, there are four different processor feature cards. The one with the 3GHz, eight-core Power7 chip costs $5,940 for the processor card plus $3,100 per core to activate each core so it can be used to run AIX, i, or Linux. That works out to $3,843 per core, which is wickedly expensive even compared to top-end x64 processors.

The six-core Power7 chip spinning at 3.3GHz costs $7,000 for the processor card plus $4,850 to activate a core, or $6,017 per core when you activate all six cores on the card. The eight-core, 3.3GHz card costs $12,400, plus $6,000 per core for activation, which works out to $7,550 per core for all of them.

And finally, the eight-core Power7 chip running at 3.55GHz, which is only available in a 32-core configuration with four processor cards, works out to costing $11,125 per core.

Those are not prices that are sustainable for entry machines, Unix or otherwise. So it is reasonable to expect IBM to get the clock speeds on the entry Power Systems servers down to 2.5GHz or so and probably kiss 3GHz.

Heaven only knows what IBM will charge for processor feature cards, but considering it was going to throw out the half-dud, four-core chips, $1,000 for a processor card in a Power 710 or 720 server and maybe $500 per core to activate seems appropriate to compete against x64 iron more effectively.

IBM has an exaggerated opinion of what its Power Systems are worth, however, and is looking for profits, not volumes, so don't expect to see anything that low. ®