IBM's Power7 pitch deconstructed
Big Blue polishes UNIX crown
Claims to fame
As all vendors accentuate the positive, IBM is throwing around a lot of claims. For instance, business partners are being told that a single Power 740 with four sockets can replace 92 Sparc T2000 servers, cutting back the number of cores by 95 per cent, the square footage of floor space by 97 per cent, and the energy used by 95 per cent. IBM also has another slide that uses the SPECint_rate2006 benchmark to "prove" a Power 750 with four-sockets (32 cores) can do 29 per cent more work than an Integrity Superdome with 64 1.6 GHz cores, but it burns only 1,950 watts instead of 11,586.
If you read the fine print, these are not the wattages of the systems as they are running the test, but the maximum power usage for data center site planning, which as far as I am concerned is playing it a bit loose. But the SPEC tests don't all track power consumption, and if you were trying to get a feeling for performance per watt, you would have to do exactly what IBM did.
The Power 750 apparently smokes four-socket Sparc, X64, and Itanium systems in terms of performance and performance per watt on the SPECint_rate2006 test. With a SPECint_rate2006 of 1,060, that smoked a Sparc M4000 server with 2.52 GHz Sparc64-VII chips (152 rating with 2,350 watts), a Sparc T5440 with 1.6 GHz Sparc T2+ chips (360 rating with 2,700 watts), an HP rx6600 with Itanium2 chips (102 rating with 1,600 watts), and an HP ProLiant DL580 G5 using older six-core Xeon 7400 chips (291 rating with 1,412 watts).
A two-socket Xeon 5500 box can do almost as much work (254 rating using the 2.93 GHz Xeon X5570, and a Westmere-EP kicker will probably be on the order of a 380 rating on the test). HP has four-socket Opteron boxes rated at nearly 400 on the SPECint_rate2006 test, but IBM didn't bring this up. And HP will be pushing up to around 800 or so with the Magny-Cours later this quarter. That Magny-Cours box will have 48 cores and no threading compared to the Power 750 with 32 cores. IBM will still be able to show more oomph per core on this test, but AMD and its partners are going to cram more cores into the box.
The other thing we noticed in the sales pitch is that IBM is assuming that a replaced machine has lower utilization (but is running at maximum electrical consumption) and that when you consolidate onto a Power7 box, you can run it at higher utilization and thereby save big bucks. Obviously, many i/OS, AIX, HP-UX, and Solaris shops are running at high utilization, so the savings IBM shows may not materialize. But just to show you one example so you can be careful of this.
In one presentation, IBM says that a Power 780 can consolidate nine 64-core Integrity (well, it said Superdome) boxes into a single Power 780 and save 91 per cent on floor space and cut the number of cores by 88 per cent. Those nine HP Integrity boxes have 576 cores running at 1.6 GHz, but IBM's comparison assumes that they are only running at 25 per cent utilization (you gotta read the fine print), while the single Power 780 with its 64 cores running at 3.8 GHz (a full rack, taking up only 7.6 square feet of floor space) hum along at 75 per cent utilization.
While IBM is offering three times the performance per core compared to the dual-core Itanium 9000/9100 series, the utilization levels it set in the comparison account for another factor of three in compression. If you assume the machines are running at the same utilization (which they would be on a test like SPECint_rate2006), then IBM has only a factor of three compression, and if you go with the full-out 128-core HP Integrity box, then the Power 780 has only a 54 per cent performance advantage if you look at the actual SPEC tests. And by the way, a Sparc Enterprise M9000, rated at 2,586 on this SPEC test, beats the 780, although by IBM's reading of the Oracle/Sun manuals it burns seven times the juice at maximum loading.
Here's another comparison IBM cooked up, which kills the ProLiant and Integrity birds with one comparison stone:
These comparisons above are based on the SPECint_rate2006 test as well, which seems to be IBM's favorite with the Power7 launch. And the CPU utilization on the unvirtualized ProLiant boxes is assumed to be low (19 per cent according to the fine print at the back of the presentation) and is at 60 per cent on the Power 750.
Ultimately, what customers need to look at to do comparisons is raw data on the systems themselves, then they need to examine benchmarks and other performance data, gather up pricing information, and finally try to weave together a picture that has more depth and breadth than the IBM sales pitch. ®
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