OS/400 Servers Over Time: iSeries to i5 to System i

Now that the System i5 machines are just getting into the hands of resellers and then customers, it is an appropriate time to take a hard look at the value that the new machines offer to OS/400 shops. In prior issues of this newsletter and its siblings in the Four Hundred family of publications, we have gone over the feeds and speeds of the new hardware and the features and functions of the new software. Now it is time to assess what kind of deal these new machines offer in a series of articles that will compare the System i5s to prior OS/400 machines and then to other platforms.

This week, I’ll take a stab at comparing the prior three generations of OS/400 platforms–the iSeries, the iSeries i5, and the System i5–to each other, and do so over the past five years. While I can–and often do–complain that IBM is not giving OS/400 shops a deal that is competitive with the other platforms of the world, the fact remains that, compared to prior generations, each OS/400 server generation generally gives pretty good improvement in price/performance. But, as I suggested might be the case in the essay from a few weeks ago called How Low Can You Go?, which I wrote prior to the System i5 announcement, the pace of price/performance improvement is slowing and IBM is, once again, giving customers better value but asking them to consume larger chunks of processing power.

If Moore’s Law, which states that you can double the transistors on a chip every 18 months or so and therefore double its performance (by cranking the clock, adding cache, adding more cores, or doing a mix of the three), is a blessing to customers and server makers alike, it is also a curse. While many workloads are taking off like crazy in the data centers of the world, no one is adding OLTP users at the rate that Moore’s Law would allow. There are very few companies in the world that are doubling their end users over the course of 18 or even 24 months. (Craig Barrett, the chairman of chipmaker Intel, the company that Gordon Moore co-founded with Robert Noyce and Andy Grove, says that Moore’s Law is being stretched as we transition from faster clocks to multicores in chip architectures.) And even in the areas where companies do see such explosive growth, they surely are not seeing it in their online transaction processing systems. Broadly speaking, the economy is just not booming out there, and the world’s ability to consume CPWs, MIPS, FLOPS, or any other unit of processing capacity just does not grow as fast as Moore’s Law actually allows. So, to sell their products, vendors not only have to use Moore’s Law to boost performance, they have to use the knife to slash prices. Sometimes, server makers are tempted to use the law more than the knife.

This has certainly been the case in the volume server market for a number of years, where vendors keep throwing in more and more components as well as more processing power to try to keep their price points and therefore their profits. The System i5 line is no exception, as my analysis of the entry and midrange part of the line shows. Take a look at this chart and it pretty much sums of where the plain vanilla System i5 boxes compared to their older (and weaker) siblings, the first two generations of iSeries products from 2001 and 2003 and the iSeries i5 products from 2004.

Figure 1: The pace of improvement in bang for the buck for base configurations of OS/400 servers is beginning to slow.

As you can see from Figure 1, the iSeries product revamping was a major event in the life of the OS/400 platform, in terms of delivering substantially improved value to customers. I think it is safe to say that it ranks up there with the AS/400 D series announcements from 1991 and the first-generation RISC AS/400 announcements from 1995 in terms of the dramatic improvement in price/performance and dramatic lowering of the cost of performance and the lowering of the base server prices as well. Every couple of years, IBM does these big announcements, and radically changes the pricing as it improves the performance, just so it can lurch toward a better competitive position against whatever platform is out there at the time. In 1991, it was established DEC VAXen, HP 3000s, and various newbie Unix boxes; in 1995, it was established Unix boxes and newbie Windows gear; and in 2003, it was established Unix and Windows boxes and newbie Linux gear. If the world can stomach another operating system, I would say in a few years we will be due for some other new platform, but I get this feeling that no one wants another operating system.

After the lurch in bang and bang for the buck in 2003, which as you can see was a very big move indeed, IBM has made more modest adjustments to the pricing of a unit of performance even as it has doubled the performance of the boxes in moving from the Power4-based iSeries line to the Power5-based iSeries i5 line. And, with this year’s Power5+ and the System i5 line, the changes seem to be a lot less drastic.

By the way, the data for Figure 1 comes from this salient characteristics and performance table. This table includes a comparison of iSeries Model 270, iSeries 8XX, iSeries Value and Express, and System i5 Value and Express Editions. It also includes a comparison of plain vanilla (meaning, not Express-style or entry packaging) servers with different performance ranges. As I have done for the past five years, I chose machines with capacities of 25,000 transactions per minute (TPM), 50,000 TPM, and 100,000 TPM. By AS/400 standards from the 1990s, these are monster machines, but by 2006 standards, this is just the kind of performance you can pack in a midrange server.

For each machine, I have taken the base box and added a minimum respectable amount of memory and disk capacity, activated the number of processor cores shown, and added on OS/400 or i5/OS, which of course includes the DB2/400 database. I also tossed in a basic tape drive, which is getting less and less expensive every year (more so than the servers, that is for sure). I then used IBM’s Commercial Performance Workload (CPW) relative performance metrics to estimate the performance of the OS/400 machine on the TPC-C online transaction processing benchmark test. This is fairly straightforward, since the CPW test is a derivative of the TPC-C test. The prices shown are the then-current list prices for the base configurations detailed in the table. Price/performance is the list price in dollars divided by the performance in TPMs. The chart above is just a graphical representation of machines in the three power bands shown in the larger table.

Some observations about the changes in the OS/400 server line over time. First of all, the amount of performance in the entry products–the Model 270, Model 800, iSeries i5 Express, and System i5 Express–has not really changed all that much in the past five years. There is usually a machine with a few thousand CPWs, then another one with around 10,000 CPWs, and then a bigger box with more. And the prices do not change all that much, either. What has changed, however, is that IBM has embedded a basic amount of 5250 processing capacity in the boxes at a much lower price point. For instance, in 2001, before the so-called “Green Streak” 50 percent price cut on two Model 270s, an entry Model 270 with 30 CPWs of green-screen capacity and about 4,600 TPMs of power cost $27,500, or just under $6 per TPM. With the iSeries 800 Value Edition, which was rated at just under 3,000 TPMs and had 25 CPWs of green-screen power, IBM charged $8,795, or just over $3 per TPM. The i5 520 Value Edition had just under 5,000 TPMs of power and 30 CPWs of 5250 activated, IBM charged $11,214 for a base machine, or $2.25 per TPM. With the System i5 520 Value Edition, a base box costs $9,948 and is capable of just under 6,000 TPMs of raw oomph, or about $1.67 per TPM. That’s a big improvement in raw power.

But if you look at the machine only as a green-screen box, and therefore only care about the amount of 5250 CPW power you get, then there was a big drop from the entry Model 270 to the iSeries 800 Value Edition, going from $916 per CPW down to $352 per CPW. But the iSeries i5 machine cost $374 per CPW for green screen processing capacity, and the System i5 machine cost $332 per CPW. The improvement, when looked at from this angle–as many entry OS/400 shops do–is not so impressive. And, if you look at the larger entry boxes, the price of a machine based solely on its 5250 CPW processing capacity can be two, three, or four times higher. Improvements on the 5250 processing front have not been as much as many customers would have probably liked on these entry machines. But, given their workloads, many shops that have to buy a regular i5 520 or i5 550 today to get the green-screen capacity they need would simply buy a much less expensive i5 520 Express if IBM took the green screen governors off.

The other thing to notice in the table is that IBM, to its credit, has offered very large jumps in price/performance over the past five years, particularly for machines in the 25,000 TPM and 50,000 TPM price bands. For the machines I configured, both Standard Edition and Enterprise Edition boxes had price/performance increases in the neighborhood of 60 to 65 percent compared to prior iSeries 8XX boxes with minimum and maximum 5250 interactive features. In 2004, the price/performance increased were more muted, but still quite large, particularly for the machines in the 100,000 TPM class. And with the System i5 launch, IBM delivered some pretty big performance increases and in some cases chopped the prices a little, yielding good bang for the buck improvements for smaller machines, not as impressive ones for the mid-sized machines, and–somewhat surprisingly–some backsliding on price/performance for the i5 570s. Remember, these are configured machines with processor, z/OS, and Enterprise Enablement activations, not just barebones boxes. IBM more than doubled the cost of processor activations with the System i5 as it moved from 1.65 GHz Power5 to 2.2 GHz Power5+ processors, and it raised the price of z/OS activations to $59,000 per core from $45,000. This money adds up.

I think that customers who need a machine in the 100,000 TPM power class have a real quandary on their hands. They can get a 4/8-way capable i5 570, as I put in the table, or they can get a cheaper i5 550 that has slightly slower processors but no expansion beyond four cores.

Incidentally, for the non-Express machines, I chose boxes that had expansion room rather than choosing a fully loaded but less expensive model lower down in the line. That was intentional. I don’t think it is a good idea to max out a brand new box, no matter what kind of server you are talking about. It is better to pay a little extra for some expansion capacity, unless you are dead sure your workloads are not going to suddenly grow. If your workloads are stable, then by all means, downshift in the product line and load up a cheaper, smaller i5 box.