IBM Finishes Up Power5+ Rollout on System p5 Servers

Published: August 29, 2006

by Timothy Prickett Morgan

IBM last week announced that it has completed the rollout of its Power5+ processors into its System p5 line, putting the dual-core 2.1 GHz chips into its entry AIX server line. The revamped products also support the Power5+ quad-core modules (QCMs), which IBM first introduced last fall in its midrange Unix servers. The QCMs cram two dual-core Power5+ chips onto a single chip package, allowing IBM to double the core count per chip socket in the servers.

IBM was, as we all know, the pioneer in dual-core processors, starting with the Power4 chip back in the fall of 2001. But IBM's chip and system designers did not think five years ago, when the "Squadron" Power5 chip design project was started, that moving to four cores on a single chip die was necessarily the right architectural move. In fact, the future Power6 chip, due in 2007, is also a dual-core chip, like the Power4 and Power5 chips. But, with power and cooling becoming big issues in the data center in the past two years and with AMD and Intel working on quad-core processors, IBM had to do something to boost the performance of the Power server line last year to stay ahead of the price/performance curve.

So, IBM took a page out of the Hewlett-Packard's playbook and crammed two Power5+ cores into one chip module, creating a quasi-quad-core chip. HP did this years ago, in fact, with IBM's help. IBM Microelectronics was the chip foundry for the PA-8800 chip and the dual-core PA-8900 chip, which wasn't a true dual-core, single-die chip but rather two PA-8800 cores with a baby chipset and some cache all on a single package. HP also created the mx2 dual Itanium modules when Intel was caught flatfooted by IBM's Power4 chips, putting two "Madison" single-core Itaniums on a single package.

To cram two chips--single core or dual core, it doesn't matter--in the same package as what a single chip uses requires some sacrifices. To double the core count, which is important for some workloads, you have to slow down the clock speed so the chips don't melt. In IBM's case, the initial QCM chips ran at 1.5 GHz compared to the 1.9 GHz of the Power5+ chips last year. This summer, IBM has ramped the speed of the dual-core module (DCM) Power5+ chips to 2.1 GHz and 2.2 GHz, and the QCMs are scaled back to 1.65 GHz.

The difference in performance can be dramatic comparing DCM and QCM machines, but the real goal IBM has with the QCM machines is to meet or exceed the per-core bang for the buck of any AMD Opteron-based server on the market--including its own. For instance, a p5 550 box with four 2.1 GHz cores (that's two DCMs) has an IBM relative performance (rPerf) rating of 24.86, while the same box with two 1.65 GHz QCMs (for a total of eight cores) is rated at 38.34 on the rPerf scale. That's a 54 percent increase in performance, for very little extra cost to customers. For transaction processing and infrastructure workloads where clock speed is not a big issue, the System p5 Q variants will offer the best bang for the buck.

"We take Sun and HP Opteron machines as serious competition," explains Karl Freund, vice president of product marketing for IBM's System p5 division within its Systems and Technology Group. "We cannot charge a premium for our performance. So these machines are priced right on top of Opteron-based machines. If our pricing is more than $2 off the price of an Opteron machine, my team still has work to do."

Intel is, of course, getting ready to launch its dual-core "Tulsa" Xeon MP processors next week, promising about 70 percent more performance thanks in large part to large cache memory. Intel says it will have its own quasi-quad, the "Clovertown" Xeon DP, to market before the end of the year--right smack in the same part of the market where IBM's new entry System p5 boxes are aimed. And AMD is saying that it will get its "Deerfield" Opterons in the field by the middle of next year, which are true quad-core processors. Beyond that, Intel is working on "Tukwila" quad-core Itaniums, too, due in 2008.

There are four new entry System p5 servers, and they come in so-called Express configurations as well as plain vanilla barebones boxes. With Express configurations, IBM puts in the processors as well as a reasonable amount of main memory and a few disk drives and gives customers a slight price break because it doesn't have to build to order. In addition, IBM is also creating Solution Editions, which are machines that are more fully configured and are explicitly created to run specific application software stacks such as SAP or Oracle. IBM has sold Solution Editions on its Power-based iSeries and System i5 family for years now, and is copying the idea for the Unix server market.

The p5 505 is the single-socket, 1U rack-mounted entry server in the p5 line, and it now has four different processor configurations. There is a DCM with one core activated running at 1.9 GHz with no L3 cache, a two-core version running at either 1.9 GHz or 2.1 GHz with 36 MB of L3 cache on the DCM, or a QCM with four 1.65 GHz cores and two 36 MB L3 caches. The p5 505 and 505Q models support from 1 GB to 32 GB of DDR2 main memory and have two hot-plug SCSI disks and two PCI-X peripheral slots. The base box has two 1 Gigabit Ethernet ports, but can have optional 4 Gigabit Fibre Channel or 10 Gigabit Ethernet I/O adapters. The base p5 505 Express comes with a single 1.65 GHz core, 1 GB of memory, and two 73.4 GB disks; it costs $3,399. With two 2.1 GHz cores, 2 GB of memory, and the two disks, it costs $5,094. Neither price includes an operating system. The p5 505Q box costs $5,505 with four 1.65 GHz cores, 4 GB of memory, and two disks. If you are running OLTP or infrastructure workloads, this is a better box than the model with two 2.1 GHz cores. For essentially the same money, you get a machine with 2 GB more memory that can do 50 percent more work.

The p5 510 comes with 1.9 GHz or 2.1 GHz Power5+ DCMs or 1.5 GHz or 1.65 GHz QCMs. This is a single-socket machine, just like the p5 505, and those machines using the QCMs are called the p5 510Q. This box supports the same 1 GB to 32 GB of main memory, but being in a 2U form factor, it can support up to four disks and three PCI-X slots. IBM is charging under $200 for the boost to the 2.1 GHz DCM on this machine compared to the 1.9 GHz version. A p5 510 box, a single 2.1 GHz core, 1 GB of memory, and two disks costs $4,455. Activating the second core and adding another 1 GB of memory boosts the price to $5,483. With four 1.65 GHz cores (using the QCM), the p5 510Q costs $5,830 with 4 GB of memory and two disks. Again, this is a no-brainer. If your workloads can make use of the extra cores, get the QCM models.

The p5 520 has been updated with faster Power5+ DCMs and QCMs, too. This machine is based on essentially the same single-socket motherboard as the p5 510, but the board has six PCI-X slots and the 520 chassis is a 4U rack-mounted unit that has room for up to eight internal disks and up to four external drive bays, each with a dozen disks. The p5 520 is supporting the same 1.9 GHz or 2.1 GHz Power5+ DCMs or 1.5 GHz or 1.65 GHz QCMs as the p5 510. In addition to the Fibre Channel and 10GigE connectivity, this box also supports 4X InfiniBand switches. With one 2.1 GHz core activated, 1 GB of memory, and two disks, the p5 520 costs $5,699. Activating a second 2.1 GHz core and adding 1 GB of memory boosts the price to $11,896. With four 1.65 GHz cores using the QCM, the price only rises to $12,999 on a machine with 4 GB of memory and two disks.

Finally, the p5 550, which is a two-socket machine, has been updated with the faster 2.1 GHz DCM and the 1.65 QCM. (The older 1.9 GHz DCMs and 1.5 GHz QCMs are also available on this machine, should customers want them.) The p5 550 supports up to 64 GB of DDR2 main memory and has five PCI-X slots. It comes in the same 4U chassis as the p5 520, but can support up to a dozen external drive bays, for a total of 144 external disks. A p5 520 with two 2.1 GHz cores, 4 GB of memory, and two disks costs $14,379. Adding two more cores and 4 GB of memory increases the price to $22,631. With four 1.65 cores, 8 GB of memory, and two disks, the p5 550Q costs $17,627. And with eight cores, 16 GB of memory, and two disks, it costs $30,731.

IBM's aggressive pricing on the QCMs in these four System p5 machines would seem to suggest that the company can make 1.5 GHz and 1.65 GHz Power5+ chips in much higher volumes than it can 1.9 GHz and 2.1 GHz chips. This stands to reason, since this is how it is in the chip business--the lower the clock speed, the higher the yield; the higher the yield, the lower the unit cost. Moreover, IBM's pricing also suggests that even with the extra cost of putting two chips in the packaging where one chip used to be, Big Blue can do so at such a price that it is basically giving customers the QCM (which has about 50 percent more oomph) for the price of a DCM. It is reasonable to expect that IBM will do the same thing with the future Power6 chips, starting with DCMs and adding QCMs as yields improve and customers demand more bang for the buck.

IBM's own AIX 5L 5.2 or 5.3 Unix variant is supported on all of the new machines, as is Novell's SUSE Linux Enterprise Server 9 or 10, and Red Hat's Enterprise Linux AS 4. AIX costs $150 per core plus $299 per server per year for software maintenance. RHEL AS 4 costs $315 for a standard subscription with 9x5 business hour support and $1,165 for premium support. SLES 9 costs $315 for the license and $945 for an annual support contract. IBM is not yet offering SLES 10 on the boxes, but Novell's pricing is lower for the initial license and the support contracts than these levels.

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