OS/400 Servers Over Time: Stacking Up the Big Boxes

Last week, we took a walk down Memory Lane for OS/400 server price/performance as it relates to small and midrange OS/400 servers in various power ranges, and this week, I wanted to examine how the biggest, baddest boxes match up across the past six years of the iSeries and System i5 product lines. As has been the case for years, the improvements in price/performance for the OS/400 line are slowing–particularly for large machines supporting large green-screen workloads.

In fact, as was the case in a few comparisons for bigger midrange boxes in last week’s lineup of i5 520, i5 550, and i5 570 machines, the price/performance of some configurations actually got worse when you activate processors, add on i5/OS licenses, and add some memory to the machines. How can this be, you ask? Well, this is what happens when there is a lack of strong competition–either direct or otherwise–for OS/400 workloads. There are a number of other factors at work as well.

First and foremost, even though the i5 570 machines using 2.2 GHz processors can scale from 8,400 to 58,500 Commercial Performance Workload (CPW) units of processing power using from two to 16 processor cores, and the i5 595 using from eight to 64 of the 1.9 GHz Power5 cores can scale from 26,700 to 184,000 CPWs of performance, there are very, very few–if any–customers in the world who deploy that much green-screen processing capacity. According to IBM’s estimates last year, it didn’t really expect anyone to need any more than about four cores of green-screen capacity, which is in the neighborhood of 12,000 CPWs using the 1.65 GHz Power5s. So why did IBM bother to make a 16-core i5 570 or a 64-way i5 595?

Well, the System p5 (formerly pSeries) AIX server line does have customers who need to deploy such large machines, and if IBM has to go through the trouble of making a big “Squadron” box for one group of customers–AIX users–it is not that difficult to make it for the another set of customers–OS/400 users. But there is more to it than just the fact that engineers had already created the hardware and it doesn’t take that much effort to tune i5/OS (the current moniker for OS/400) reasonably well to run on this expansive hardware. The sales pitch for the System i5 is focused on the concepts of server consolidation and infrastructure simplification, which means customers with multiple OS/400 footprints are being encouraged to take many AS/400 and iSeries footprints and put them into multiple logical partitions, perhaps running different time zones and supporting different languages, which is necessary for multinational corporations. This has been part of the sales pitch for more than six years, so it is not new. What is new is that the iSeries i5 and the System i5 have enough oomph to actually consolidate some pretty big workloads on it, and it has enough logical partitions to support.

But the impressive scalability is about more than just server consolidation. There is another, special flavor of server consolidation that IBM calls infrastructure simplification, which means not just consolidating multiple OS/400 images onto a single System i5 server, but taking Windows, Unix, and Linux workloads and bringing them to the box as well, running their jobs–but not necessarily their actual operating systems–within logical partitions. With the new hypervisor that came with the iSeries i5 systems (concurrent with i5/OS V5R3) in May 2004, IBM was able to put native AIX workloads into logical partitions; Linux partitions have been available for more than five years, but really only matured with the Linux 2.6 kernel and the Virtualization Engine hypervisor that dates from this time.

If it hasn’t become apparent to you in the past two years, let me make it clear to you now: All that extra power is not really aimed at OS/400 workloads, and it is financially less attractive with the System i5 machines from 2006 than it was with the iSeries i5 boxes from 2004. While you can make the case that consolidating many entry OS/400 footprints into an i5 570 or cramming many midrange OS/400 servers into an i5 595, the ante to buy into one of these systems to support green-screen workloads is very high. And which IBM cut back on the base i5/OS activations for the i5 570 machines last summer–thereby reducing its initial price–IBM has gradually raised the price of an i5/OS license from $45,000 to $50,000 and now to $59,000 per core even as it cut the price of i5/OS on entry machines to $24,000 per core from $45,000. Moreover, processor activations in the new machines are quite high. For instance, it costs $16,199 to activate a 2.2 GHz Power5+ core in the new i5 570, and it costs $32,500 to activate a 1.9 GHz Power5 core on the i5 595. These costs add up when you roll i5/OS and its Enterprise Enablement (meaning 5250 support) over those processors.

But Linux and AIX do not include an integrated database management system and they do not require 5250 support, and while the cost of activating Power5 and Power5+ cores is pretty high compared to buying little rack or tower servers, the cost of administrators for maintaining Windows boxes, which are everywhere at OS/400 shops, and Linux and AIX machines, which are at some OS/400 shops, is very high. A server administrator is kept pretty busy managing a few dozen servers, but managing a few dozen partitions and the centralized storage behind them can be a lot easier. And, because logical partitions are flexible, an intelligently designed i5 consolidation machine can be more resilient and deal with workload peaks better. It is far easier and economically justifiable to buy 20 percent extra computing capacity on a virtualized machine to cope with peaks than it is to cope with 200 servers that are running at 10 to 15 percent of capacity.

Having said all of that, it is nonetheless interesting to examine the cost of support 5250 workloads on big OS/400 iron over time, for those customers who do need to do this. And while pricing didn’t improve for a heavily loaded, 64-core System i5 595 box–it does 12 percent more work, but costs 21 percent more with 512 GB of main memory–the price/performance of reasonably configured i5 570 and i5 595 machines did come down.

To make my comparisons, I looked at machines with 25,000 CPWs and 35,000 CPWs of performance (roughly 238,600 and 334,000 TPC-C transactions per minute). I’ve made this comparison for the past few years, but I cast it back beyond the 2003 data I showed with the iSeries i5 launch in May 2004, back to the 2001 generation of iSeries machines. The price/performance curve has a very similar shape to the one I drew for machines last week. With the big iSeries revamp in January 2003, when IBM applied “Green Streak” discount pricing to the iSeries line and introduced the concept of the Standard Edition and Enterprise Edition packaging for i5/OS.

As you can see from the iSeries-i5-System i5 comparison table I built, the cost of a unit of processing power on a big iSeries box circa 2001 was pretty high. The top-end box, a 24-way Model 840, had a rating of 20,200 CPWs, making it one of the most powerful servers anyone had ever shipped (including IBM’s zSeries division, by the way). But with full 5250 interactive processing, that machine cost $7.2 million, yielding a price performance of about $354 per CPW. And, you have to remember this, too: It used to be worse than that!. With the iSeries revamp in early 2003, a Power4-based machine using processors that ran more than twice as fast cost a mere $2.2 million for 24,650 CPWs of power, or about $91 per CPW. This was a 74 percent increase in price performance.

With the System i5 launch in January, IBM moved from 1.65 GHz Power5 to 2.2 GHz Power5+ processors in the i5 570s, and even with higher i5/OS licensing costs and higher processor core activation fees, an i5 570 in the 25,000 CPW performance range offered about 17 percent better bang for the buck. And for similarly powerful i5 595s, price/performance improved by about 10 percent. You might say that sounds great, but the gap in price/performance between the i5 570 and i5 590 is large. It costs nearly twice as much for a base i5 595 machine that does 26,700 CPWs as it does for a two-chassis i5 570 rated at around 23,900 CPWs. When you fully load an i5 595, as I explained above, price/performance was worse, not better, for a machine loaded to the teeth with 5250 green-screen capacity. Significantly, the base machine cost just under $10.5 million. This is a lot of money. But, ironically, the bang for the buck for the big i5 595 box is in the same range as for the smaller i5 570s.

The message in this pricing is this: if you are going to consolidate on a big iron i5, pick the right box. Because if you don’t, you will overpay.

For larger machines in the 35,000 CPW performance range, the story is much the same, as you can see from the table. I could have scaled the table up further, but these capacities are already very large for OS/400 shops. That is why I configured the i5 595 Big Bad Boxes, which show the absolutely best price/performance you are going to see for large OS/400 servers aside from base configurations of the i5 570s. In between these two extremes, plan carefully and watch out for the bell curve.

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