IBM Gets Power6 Chips into Entry System p Servers

Published: January 31, 2008

by Timothy Prickett Morgan

The wait for the Power6 processors to make their way down into the low-end of the System p line is over--or, very nearly so. On Tuesday, IBM did what its top brass said it would do a few weeks ago: started ramping up the Power6 platform on its entry servers and chasing customers with the high performance, respectable thermals, and very good virtualization embodied in the System p line, the Power6 processors, the AIX 6.1 operating system, and the related PowerVM hypervisor, formerly known as Advanced Power Virtualization.

The Power6 processors were put into the System p line last May in the System p 570, which spans from two to 16 cores in a single system image. That box began shipping in June, and contributed mightily to IBM's third and fourth quarter financials. A System i variant sporting a tweaked i5/OS V5R4 was announced in July last year and began shipping in September, and did its part to boost sales in the fourth quarter of 2007. Now, IBM wants to add another variant to its entry and midrange machines. And in doing so, it looks like IBM is making its product line simpler and is keeping the existing branding for its servers. So rather than call these machines the 620 and 650 servers, they have the same names that the Power5 and Power5+ machines had: the 520 and 550. That said, there are a lot of different electronics in the Power6-based 520s and 550s that is not in the older versions, and they are different enough that IBM probably should have renamed them. But Big Blue has always had its own ideas about naming conventions, marketing, and related issues. When you are a $100 billion IT supplier, you can indulge in your own eccentricities, too.

The new System p 520 Express machine has a motherboard design that allows up to two planar boards, each with a single dual-core Power6 processor, to be added to the box. IBM is selling configurations with one, two, or four cores running at 4.2 GHz inside this box. Each processor socket has 8 MB of L2 cache, which means the single-core variant gets it all to itself, while the two- and four-core variants get 4 MB per core. For some reason, the chip package IBM is putting into the System p 520 Express does not have any L3 cache memory on the processor card; the packaging in the System p 570 and System i 570 machines has 32 MB of L3 cache off chip that is shared by each dual-core processor. It looks like the new 520 and 550 designs have a single processor per processor card, with a 32 MB cache on that processor card only for 550 and 570 machines. (My guess is that these processor cards are all essentially the same across the Power6 server line.)

The Power6 chip is arguably IBM's most sophisticated processor, and includes decimal math units and Altivec VMX vector co-processors as well as four-threads running at the highest clock speeds available in the IT space. They offer approximately 50 percent more oomph than IBM's Power5+ processors, which were also dual-core processors but which had significantly lower clock speeds. This AltiVec feature is disabled in the 520 Express machine, but is available in the 550 Express machine and in the existing 570 machines in the System p and System i lines. IBM currently has Power6 cores running at 3.5 GHz, 4 GHz (in the JS22 blade server), 4.2 GHz, and 4.7 GHz. Not all of these different speeds are available in the two new machines announced this week.

The System p 520 Express offers a memory capacity that ranges from 1 GB to 64 GB (using DDR2 memory), but the single-core machine tops out at 16 GB and the two-core machine maxxes out at 32 GB if you read the fine print in the spec sheets. Rather than using low-energy 2.5-inch form factor disks in this entry machine, as Hewlett-Packard and Sun Microsystems are offering in their latest Unix boxes, IBM is sticking to 3.5-inch SAS disks that spin at 15K RPM. IBM obviously believes customers are more interested in the performance of disk subsystems in the 520 Express box that low energy, and it could well offer 2.5-inch disks as an option in the future. In any event, the 520 Express server has room for six SAS drives, and IBM is selling drives with 73.4 GB, 146.8 GB, and 300 GB capacities. That's 1.8 TB of internal capacity, which can be expanded to 30.6 TB with up to eight optional 7311-D20 I/O drawers that can be linked back into the 520 Express server. The server includes a 3G SAS disk controller on the motherboard, with a RAID 5 daughter card that plugs into the board if customers want data protection. In terms of other peripheral expansion, the box has two media bays for DVDs and CDs, two PCI-X slots, three PCI-Express x8 slots, and two Gigabit Ethernet ports. Customers can add two more Gigabit Ethernet ports or two 10 Gigabit Ethernet ports.

All of this is crammed into a 4U rack-mounted unit or a similarly sized deskside tower. With a single core, the 520 Express machine based on the 4.2 GHz Power6 chip has a relative performance (rPerf) rating of 8.39, and with two cores it is rated at 15.95 and with four cores it is rated at 31.48.

The base Express 520 box (technically the 8203 machine in IBM's configurator) comes with one 4.2 GHz core, 2 GB of memory, and two 73.4 GB disks; it costs $5,576. An AIX license costs $150 and a year of Software Maintenance costs $299. The two-core variant costs $11,765 with 4 GB of memory and two disks; AIX costs $300 and Software Maintenance for a year costs $598. With four cores in the 520 Express plus 8 GB of memory and the two disks, the cost of the machine rises to $16,994. AIX costs $600 and Software Maintenance costs $1,196 for a year.

With the System p 550 Express machine, IBM is offering customers either 3.5 GHz or 4.2 GHz Power6 cores and from 2 to 8 of them inside the same 4U form factor. In fact, from the outside, it looks exactly like the new 520 box. (The old 550 boxes based on Power5 and Power5 plus were two-socket machines, but the new 550 has four sockets. Similarly, the old 520s were single socket machines, but are now two socket boxes. Why this doesn't make them different machines is beyond me.) The 550 Express machine with 3.5 GHz Power6 cores offers from 1 GB to 128 GB of main memory expansion while the version using 4.2 GHz chips can be ratcheted up to 256 GB of main memory. The machine has the same internal and external disk capacity as the new System p 520, the same integrated SAS controller with a RAID 5 option, and the same peripheral ports. The performance of the System p 550 Express based on the Power6 chip ranges from 15.85 to 58.8 rPerfs using from two to eight of the 3.5 GHz Power6 cores and from 18.38 to 68.2 rPerfs using the 4.2 GHz Power6 cores.

Basically, the Power6-based System p machines now cover the performance range of the Power5+ dual-core machines (the 520 and 550) on up to the variants of the System p line that had quad-core modules (with two Power5+ chips in a single package, used in the 560Q machines last year). It seems unlikely that IBM will do quad-core modules based on Power6 chips, not so long as Advanced Micro Devices is having issues with its "Barcelona" quad-core Opterons, Intel is nowhere near delivering its quad-core "Tukwila" Itaniums, and Sun Microsystems is not yet shipping its multicore "Rock" UltraSparc RK processors. (Intel's quad-core "Harpertown" Xeons might convince IBM to do quad-core module implementations of Power6 processors, however. Just to keep the price/performance advantage in the favor of the System p line.

Anyway, the base System p 550 comes with two 3.5 GHz Power6 cores, 4 GB of main memory, and two disk drives; it costs $25,247. AIX costs $770 and a year of Software Maintenance costs $898. The same configuration using the 4.2 GHz cores costs $35,249, which is an extra 40 percent more dough for 16 percent more performance, as reckoned by rPerf.

If you think this price premium for performance indicates that IBM has lots of 4.2 GHz Power6 parts lying around, I got this here Brooklyn Bridge I can give you a deal on. . . . I think that no matter what IBM says or hints off the record, yields on Power6 chips have been low enough to hold up product launches for many months, and the fact that 4.7 GHz parts are not in these two new servers only goes to make the case even more. Look at it this way: With four cores, the new 550 box is rated at 31.27 rPerfs using 3.5 GHz Power6 cores, but the 550 with four 2.1 GHz cores was rated at 19.12 rPerfs and using quad-core modules running at 1.5 GHz, an eight-core 550 came in at 26.5 rPerfs. If IBM could widen out the spread in performance, it surely would. Which is also why I think the System i line got only 4.7 GHz parts--IBM didn't think it would sell that many, and hence the relatively low yield on the chips would not be a problem.

The point now is, Power6 machines are coming to market. And that is good news for IBM and its channel partners.

The patched version of AIX 5.3 and as well as AIX 6.1 are supported on the two new Power6 servers, and so is Novell's SUSE Linux Enterprise Server 10 SP1 and Red Hat's Enterprise Linux 4.5, 5.0, and 5.1. The new System p 520 will be available on February 29, while the 550 will be available on February 7.

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