Midrange i5s Versus the iSeries, Revisited

I did a detailed comparison in early June of entry and midrange models of the eServer i5s to the prior generation of iSeries machines. A lot of things related to i5 pricing changed through a succession of i5 announcements, culminating with the launch of the four-way iSeries Model 550 server. These changes warrant a second look at how the i5s rate against the iSeries, as well as a comparison of how the different i5s stack up against one another.

Aside from the launch of the i5 Model 550, the most significant change that IBM announced regarding i5 pricing was the way it changed i5/OS Standard Edition and Enterprise Edition pricing and packaging in July, when the company also rolled out the fully extended i5 Model 570 servers, which now span from one to 16 Power5 processors. IBM partially decoupled 5250 processing capacity, which it calls Enterprise Enablement, from i5/OS Enterprise Edition, and it is now charging specifically for this capability. IBM is also activating Power5 cores, but is enabling i5/OS or 5250 processing for only some of these cores. In some cases, such as with the Model 570, 5250 capacity is enabled for processors that have not even been activated yet. The effect is that, as customers activate i5/OS Enterprise Edition on Power5 cores, they do not incur additional Enterprise Enablement fees. They have effectively prepaid for 5250 OLTP capabilities.

Suffice it to say, all of the changes with the i5 line are a bit confusing, which is why quite a number of you sent me e-mails over the past few weeks asking me to bring it all together in my traditional salient characteristics tables. I couldn’t keep it all straight, either, so it sounded like a good idea to me, too. Some of the performance data in the updated eServer i5 salient characteristics table has been tweaked, as IBM has slightly revised its numbers. I am still trying to find out what the base active CPW ratings are on the larger Model 570 boxes; the IBM documentation doesn’t explain what each incremental Power5 core adds to the complex in terms of aggregate CPW performance. (My guesses are usually within about 5 percent or less, so plan accordingly.) The notes at the bottom detail the fees for activating dormant Power5 cores, licensing i5/OS for a core, and adding 5250 OLTP capacity to a core. Later in the article, I have gone to the trouble of building reasonable base configurations of the i5 machines compared with last year’s iSeries machines (at last year’s prices) to show you how much bang for the buck they offer. But first, let’s talk a bit about IBM’s official i5 positioning.

IBM’S LATEST I5 POSITIONING RELATIVE TO THE ISERIES

With so many changes to the iSeries line, IBM was compelled to put a product positioning note inside the Model 550 announcement that explained what it believed were the best midrange i5 machines for particular customers, based on where they were coming from in the iSeries line.

IBM did not talk about the entry Model 520 machines in this document, but the Express versions of these machines are clearly aimed at replacing the iSeries Model 800 machines running OS/400 Value, Standard, and Advanced Editions on preconfigured systems (as opposed to essentially empty server chassis, as is the case with the modern OS/400 server). The pricing on the Model 520 Express boxes is a little higher than the Model 800 for the smaller machines, but they have a lot more power; and IBM actually geared the larger Model 520 Express machine to have roughly the same performance as the Model 800 Advanced box, with a slightly lower price. (You can see updated price and performance comparisons in the second monster table in this story, which details the current and former i5 pricing against the iSeries pricing.) IBM’s pricing and positioning of the Model 520 Express boxes has not changed appreciably since May, when these servers were announced.

But the advent of the Model 550, as well as changes in the pricing for Model 520 and Model 570 servers, have made it more problematic trying to figure out which i5 model to buy. The fact that there are no upgrade paths among the Model 520, Model 550, and Model 570 servers means you have to be very careful about what box you pick. It is ironic (almost bordering on mean or senseless, take your pick) that the current i5 line has the most commonality of computer components that we have seen across OS/400 servers since their launch in 1988, and yet upgrades between the server models in the i5 line are not available. I fail to see why a Model 520 cannot be upgraded all the way through a Model 550 to a Model 570. They use the same processors and the same chassis with some minor modifications. Go figure. IBM must have a strong business case for making customers think really hard about what box they pick and then living with that choice. IBM may believe that customer workloads on the i5s will not grow very fast, and that the expandability in any of the i5 boxes will meet the needs of the vast majority of customers, provided they pick the right box to start with.

According to IBM’s latest positioning, customers who are considering buying or are currently using the iSeries Model 810 should look first at the i5 Model 550. Customers looking at the Model 825 (with three to six Power4 cores) are advised to look at the Model 550. Those looking at the Model 870 (with five to eight Power4 cores) are told by IBM that if they are going to run i5/OS Standard Edition, they can still rely on the Model 550, but that the Model 570 has more I/O and memory capacity and more upgradeability in general. And, as my analysis below shows, the Model 570 is in many cases less expensive than the Model 520 (though not by much) with a lot of 5250 OLTP capacity activated. The Model 570 will probably have yet another virtue: I suspect (but do not know for certain) that it will be upgradeable to the future 64-way i5 Model 590.

THE MODEL I5’S BY THE NUMBERS

In the iSeries-versus-i5 price/performance comparison that was published in this newsletter in June, I took the most obvious comparisons between the two families of machines but did not go through every possible variant in the i5 line. With the advent of the Model 550, there is a lot of overlap among the capabilities in the Model 520, Model 550, and Model 570 machines. So in this iteration of the comparison table, I have configured each i5 machine with one, two, or four processors activated, running both i5/OS Standard and Enterprise Editions. (The Model 520 only goes up to two cores, of course.) The Enterprise Edition machines are configured with i5/OS licenses for the cores shown activated, so you can get a sense of what 5250 OLTP costs.

What this table shows is that you have to be careful about which i5 you chose. A single-core i5 Model 520 under the new pricing offers excellent bang for the buck compared with the iSeries Model 810, and is a little different from the May i5 pricing, in that disk drive prices have come down. (I left in the May 2004 prices for the i5 servers just so you could see that i5 prices did not change all that much, even though the means of building the prices have changed a lot. The May prices are to the far right of the table.)

You might think that the smartest thing is to buy a single-core Model 550 or Model 570 instead of a Model 520. While you will have more expandability by doing this, you will pay nearly twice as much for a unit of processing capacity in a Standard Edition machine and even more for a machine running Enterprise Edition. Not a strategy that your company’s owner, president, or CEO is going to accept very easily.

As you move up to two-way Power5 machines, the Model 520 is a little cheaper than the Model 550 running Standard Edition and is a lot cheaper than the Model 550 running Enterprise Edition. It costs $281,850 to buy a Model 520 with 4 GB of main memory, 70 GB of storage, a disk controller, and i5/OS Enterprise Edition, with 5250 enabled on both processors; a similarly configured Model 550 with exactly the same performance costs $422,850, while a similarly configured Model 570 (that’s the so-called 1/2-way) only costs $364,550. The Model 550 base hardware, operating system, database, and 5250 OLTP is more expensive, but this machine has two more cores that can be activated (the Model 570 has to be upgraded), and the Model 550 can also have its price brought down through Solution Edition pricing, which shaves off $60,000 if you buy one of the software suites supported on it. The Model 550 also is in the P20 software tier, compared with the P30 tier for the Model 570 1/2-way and the Model 520 two-way. What you pay to IBM in hardware costs you might save in software costs by acquiring a Model 550.

Again, on the Model 550 with four cores activated, the Standard Edition is a bit cheaper on this box than it is on the Model 570 2/4-way box, but Enterprise Edition with full 5250 activation is considerably more expensive. A Model 550 with four 1.65-GHz cores, 8 GB of main memory, and i5/OS, with the full 5250 OLTP capability on those four cores, costs $720,000 and is rated at 12,000 CPWs. (That’s about 116,500 transactions per minute on the TPC-C online transaction processing benchmark test.) IBM reckons that very few OS/400 shops will ever need to go beyond 12,000 CPWs, so this is, at least as far as 5250 RPG and COBOL applications are concerned, a big box, even though it is a four-way server. A Model 570 with the same configuration has a list price of $615,230. Again, the Model 550 is in the lower software tier and can be acquired with a Solution Edition pricing if you happen to use one of the third-party application packages that are entitled to this pricing.

No matter what, the important thing to remember is that you have choices with the i5s, and that they are, despite the pricing complexity, a lot less expensive and more capable than the iSeries machines they replace.

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