The Power Systems 550 M50 Versus Its Predecessors

Published: July 7, 2008

by Timothy Prickett Morgan

When IBM said that it was mostly concerned with preserving the price points of its i-class machinery as it made the transition from the System i to Power Systems i Editions, the company wasn't kidding. With the user-priced entry Power 520 M15 and M25 editions, customers are seeing some price/performance improvements, but with the larger Power 550 M50 machine, the bang for the buck is not appreciably different from its predecessor System i 550 boxes. You can debate for yourself whether or not this matters all that much, but I think it does matter.

With every successive generation of systems and servers, customers certainly expect price/performance improvements. And the machinery based on X64 processors from Intel and Advanced Micro Devices has certainly done this over the past six years, often to a stunning degree. (I do think that the strategy of adding cores to processors is going to soon run out of gas, however. Chips with eight or more cores really need extremely multithreaded applications--the very kind that most customers do not know how to write. Vendors of system and application software are not very good at this multithreaded software design, either.) My point is, any time you are standing still in the server racket in terms of price/performance, you are a sitting duck. And while I know IBM and its reseller partners need to protect their margins to make the i game worth while, the box has to compete and show value for dollar compared to its predecessors (in this case, iSeries and System i gear) to keep customers moving ahead and to keep them from moving to other platforms.

The new Power Systems 550 machine is a four-socket, eight-core Power6 system when sold as an AIX and Linux Edition, but mysteriously tops out as a four-core machine with the i Edition. (When you consider that the AIX and Linux Edition is showing roughly twice the online transaction processing performance running DB2 than the same iron running i5/OS V5R4 or i 6.1 and its integrated DB2 variant, this is exactly backward when you consider that i shops almost exclusively run OLTP workloads.) The Power 550 machine, which goes by the 9409-M50 designation, is not a user-priced box like the prior System i 515 and 525 and the new Power 520 boxes, which I compared to earlier System i 520 machines a month ago. The 550-class machines have per-core pricing for software, like the existing Power6-based System i 570, which was rebranded as the Power 570 earlier this year.

The 9409-M50 box has from one to four Power6 cores running at 4.2 GHz and spans from 4,800 CPWs to 18,000 CPWs of performance on OS/400, i5/OS, and i workloads; a slower and less-expensive 3.5 GHz processor is also available. The machine spans from 2 GB to 128 GB of main memory and has up to six internal SAS drives for a maximum of 1.7 TB of internal storage. The machine also sports two HSL-2 or 12X I.O loops, for a maximum of a dozen HSL-2 or eight 12X I/O drawers, which boosts the maximum number of SAS or SCSI disk arms to 546 and the capacity up to 154 TB for this M50 box. The machine has one embedded disk controller, and using feature slots or peripheral drawers, it can host up to 60 disk controllers. The M50 server has the same three PCI-Express and two PCI-X slots as the M15 and M25 Power machines, and the system, with I/O drawers installed, can handle up to 171 peripheral cards and a maximum of 96 Gigabit Ethernet ports. The Power 550 i Edition server is in the P20 software group and started shipping on May 23.

Pricing information was not available for the Power 550 i Edition when it was announced back in April, but pricing for the so-called Express configuration, which is preconfigured by IBM and its resellers with a slight discount on the hardware, is now available since it is shipping. The Power 550 i Edition Express comes with the system unit with one 4.2 GHz core activated with i5/OS V5R4 or i 6.1, with the PowerVM Standard Edition hypervisor, and with 5250 enablement; it also has 16 GB of main memory, eight 70 GB disks, a RAID disk controller, a DVD drive, and a 36 GB 4mm tape drive, all for $140,151. It costs $40,000 to add i5/OS V5R4 or i 6.1 per core, $50,000 per core for 5250 enablement, and $1,310 per core for PowerVM Standard Edition. It costs $16,092 to add a processor card with two 4.2 GHz cores on it, and then a further $7,573 per core to turn them on. Almost all of that cost is the cost of producing the Power6 chips--trust me--and it works out to around $30,000 per Power6 chip if you assume the processor board on which it is mounted costs somewhere around $1,200 to make. (And that is crazy expensive at that for a motherboard.) AIX, i, and Linux shops buying Power 550s pay the same exact prices at list--but we all know who gets the big discounts, don't we? And we sure as hell know who doesn't get them, right?

Anyway. Make sure you call Hewlett-Packard, Oracle, and their IBM midrange replacement teams and let your reseller know they are bidding on your budget when you are doing your next upgrade into a 550-class box. I am not suggesting that you move off the i machine, mind you, but rather that you have to make Big Blue believe you might to get the kinds of discounts that Unix shops enjoy by virtue of the competition that AIX on Power faces from Sun Microsystems and HP, among others. No matter how much IBM protests, the i platform is, at least when you are talking about RPG and COBOL applications and the DB2 for i database, a proprietary platform. And that tends to mean price gouging. In the past, this was done at the list price level for Power iron and then aggravated by deep discounting on AIX boxes, and I suspect that the discounting has not gone away even as the Power iron prices have been brought to unity by the merger of the System p and System i lines.

To help make your capacity planning a bit easier--and to compel you to push for discounts--I have compared old and new 550-class machines in this pricing and performance table. This table is the companion to the Power 520 M15 and M25 table I created a month ago. Both tables calculate the cost per transaction per minute for the machines based on the CPW benchmark and my conversion of that rating to estimated TPC-C online transaction processing performance.

I have also added users for the earlier machines that did not have them to calculate the cost per user in the M15 and M25 comparisons; I added users to the 550-class machines just to make comparisons possible based on OLTP and user metrics. These 550 machines are not priced on a per user basis, however, so don't be confused. You can add many more users to the box, based on your workloads, thereby allowing a lower per-user cost. I don't think of the number of users I put on the 550-class boxes as being untypical; if anything, they are probably heavily loaded, since systems are usually bought based on their peak batch capability as much as on OLTP performance.

In the comparisons, I also removed Software Maintenance fees from all of the systems, even though IBM requires customers to buy it, because I think customers should have the choice of maintenance services or not (or IBM or otherwise) and because I want to isolate system costs from support costs. I also configured a Power 550 box with the slower 3.5 GHz processors and removed 5250 enablement from it to get something that smells like a System i 550 Standard Edition machine from the earlier product line; the other configurations have the faster 4.2 GHz processors and 5250 enablement on all cores, which makes it akin to a System i 550 Enterprise Edition machine. On the largest machines in the configurations--those with 150 or 300 users--I have doubled up the main memory, but left the processing capacity and disk capacity the same since I think they are reasonably and typically configured.

As you can see from the comparison table for the 550-class boxes, the move from 1.9 GHz Power5+ processors to 3.5 GHz Power6 processors did not change performance all that much. I estimate that a two-core Power 550 has a CPW rating of 7,750 (IBM has not, as far as I know, released performance ratings for anything but a two-core and four-core 4.2 GHz Power 550), which is only a 9.2 percent performance boost. A configured box with two 3.5 GHz cores, 8 GB of memory, eight disks, the tape drive, i 6.1 and PowerVM Standard Edition, and no 5250 enablement costs $145,269, which is actually 18.5 percent more expensive than a System i5 550 box with the same configuration. That means this Power 550 box provides a 9 percent decline in bang for the buck based on OLTP throughput and, assuming 40 users for both machines, a 19 percent decline based on per-user costs. Yikes.

If you have a need for only two Power6 cores and you don't think you will be upgrading the machine any time soon, a similarly configured System i 525--at list price--costs half as much and does almost the same amount of work. It runs i5/OS V5R4 or i 6.1, and resellers would probably be happy to give you a deal to get it out of their barn. A Power 520 M25 offers more performance than the System i 525 and even better bang for the buck, so something akin to a 30 percent discount on the System i 525 seems to bring both the new and old user-priced machines in line with each other. My point is, the M50 is not a great option if you are running workloads that don't require 5250 enablement.

However, if you are running green-screen workloads, then the M50 offers substantial price/performance improvements over the System i 550 it replaces, whether you look at it in terms of raw throughput or on a per-user basis. I am talking about a 39 percent improvement based on OLTP throughput and 20 percent based on per-user costs. The comparisons I made are based on 4.2 GHz cores, not the 3.5 GHz ones, and have 5250 enablement on both cores in the box.

Moving up to four-core configurations, the situation is much the same. Creating a hand-made, non-5250 Power 550 results in a box that offers worse value for dollar--10 percent worse based on OLTP throughput and 18 percent worse based on per-user costs--while creating a green-screen Power 550 delivers a 28 percent improvement in value for the dollar based on OLTP oomph and a 7 percent improvement based on per-user costs.

Next week, I'll take a look at how the BladeCenter S chassis and the JS12 and JS22 Power6 blade servers running the i 6.1 operating systems stack up against the entry and midrange Power Systems tower servers and their predecessors, rounding out the set of boxes that most OS/400, i5/OS, and i shops will be examining as they do their budgeting and planning. Then, it will be on up the line to the Power 570 and Power 595 boxes and their predecessors, and then on to comparisons with Unix, Windows, and Linux machinery for the Power Systems line running i 6.1.

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