How the eServer i5s Stack Up Against the iSeries

Over the past several weeks, this newsletter has gone through the eServer i5 and i5/OS V5R3 announcements, giving you the feeds and speeds on the new hardware, the new features of the software, details on pricing for components, and the reaction from the OS/400 community. This week, I want to get down to the nitty gritty: how the new i5 iron compares to last year’s iSeries iron in configured machines.

Ultimately, it is the comparison of the i5s to the iSeries that will determine how quickly existing customers buy a new machine (particularly those on older AS/400 machines without a formal upgrade path) or upgrade from an existing one into the i5 line. While being able to demonstrate big improvements in price/performance when comparing the i5 to the iSeries is a necessary condition for the i5 to thrive, it is certainly not sufficient. That is why over the next few weeks I will compare the i5s to popular Windows, Linux, and Unix servers. Any new customer evaluating the i5 either has one of these non-OS/400 boxes already or is looking at acquiring one as well to accomplish their data processing.

With the iSeries and i5 machines, the base list price that IBM provides is for the central electronics complex (CEC), not for a configured machine. The prices do not include memory, disk drives, and other features that make it a working system. The exception to this rule is the various pre-configured entry machines IBM just announced as the i5 Express servers. These are more or less working configurations, and ones that come with 1 GB or 2 GB of main memory, 70 GB of disk capacity, a 30 GB quarter-inch cartridge tape drive, a bunch of other peripherals, and a discount that ranges from 32 to 39 percent. IBM is prebuilding these i5 Express configurations and making resellers buy them in lots of 10 or 20. This allows IBM to significantly simplify manufacturing, which cuts costs. IBM is passing some of the savings through the channel to customers because it wants to drive server volumes more than it wants to have excess profits from a smaller base. IBM is taking the same approach with the pSeries line, but the discounts are nowhere near as deep for customers.

Because of this deep discounting, the Model 520 Value Edition, the entry, bare-bones machine in the new i5 line, is not a very good deal by comparison. As the comparison table I built shows, even though the base Model 520 Value Edition box has an attractive $6,388 price tag, by the time you add memory and disk to make it useful, it has essentially the same list price as the first configuration of the Model 520 Express Edition. The Model 520 Value Edition, which sells for $9,995 for a machine with 512 MB of memory and a single 35 GB disk drive, is for the absolute minimum green-screen shop (like the Model 150 and Model 170 of years gone by was). These shops want to minimize everything, including monthly maintenance. Incidentally, none of the comparison numbers excepting the Model 520 Express Edition machines include fees for Software Maintenance, which covers software updates and tech support. When you factor this in, the Express Editions for the i5s are a considerably better deal than the machines IBM sold last year.

As the table shows, the base iSeries Model 800 Value Edition from 2003 cost $8,795 and had about half of the oomph of the Model 520 Value Edition and the two smallest Model 520 Express Edition configurations (denoted by #1 and #2 in the table). The iSeries Model 800 Value Edition was short on memory and disk capacity, and the iSeries Model 800 Standard and Advanced Editions were skinny by comparison to the new machines as well. IBM was charging just under $15,000 in 2003 for an iSeries Model 800 Standard Edition with 512 MB of main memory, 36 GB of disk, and a peak processing capacity of around 2,870 transactions per minute (TPM) on the TPC-C test (those are my estimates, not IBM’s). This year, you can get the i5 Model 520 Express Edition #2, which has 2 GB of main memory, 70 GB of disk capacity, and can handle nearly 5,000 TPM of peak processing for about the same money. (In both cases, customers will need to add a lot more memory and a few more disk arms to get that peak throughput.)

When you do the math, the cost per TPM on the base configuration of the iSeries Model 800 Value Edition was about $3 per TPM, the Standard Edition was about $5 per TPM, and the Advanced Edition was about $4 per TPM. The i5 Model 520 Value Edition and Express Edition #1 machines are just over $2 per TPM, while the two larger Model 520 Express Edition machines (#2 and #3) have a price/performance in their base configurations of around $3 per TPM. Clearly, the i5 Model 520 entry machines are a much better deal, and represent a price/performance improvement of between 21 and 55 percent, depending on the comparison you make.

Last spring, when I built similar comparison tables to evaluate the bang for the buck of the first and second generation iSeries machines, I compared two-way, four-way, and eight-way configurations. I did this because the processing technology did not make a substantial change between late 2001 and early 2003. IBM was still using a mix of S-Star PowerPC and Power4 processors in both lines. This time around, I need to compare S-Star and Power4 boxes to Power5 boxes, and there is a big jump in per-processor performance. Counting CPUs, which is how many of us think about servers, doesn’t make much sense. That’s why this time around I am bracketing performance in transaction processing performance bands. Because it works out this way based on IBM’s CPW ratings for the iSeries and i5 machines, the brackets came out to 25,000 TPM, 50,000 TPM, and 100,000 TPM ranges with the i5 Model 520 and 570 machines. Again, the TPM ratings for all of the machines in the table are based on my own estimates of the throughput a heavily configured machine would have on the TPC-C online transaction processing benchmark test. I know I am mixing performance of a heavily configured machine and pricing on a base processor, but it is the best metric we have that can span all processor families. I want to gauge the value of a base processor configuration and isolate the CEC, operating system, and database cost.

For these comparisons, I have configured both iSeries and i5 machines in each performance band with both OS/400 Standard Edition (which has no green-screen processing capability) and OS/400 Enterprise Edition (which has 5250 processing fully activated).

Last year, as you moved from a two-way machine to a four-way machine up to an eight-way machine, the cost of computing power in the iSeries line went up considerably. As the table shows, the iSeries Model 810 was a considerably better bargain than the Model 870, whether it was running OS/400 Standard or Enterprise Edition. Perhaps more significantly, on smaller OS/400 server configurations, IBM has normalized the pricing difference (whether intentionally or accidentally) between machines configured with OS/400 Enterprise Edition compared to machines configured with OS/400 Standard Edition. As a rule of thumb, it looks like IBM is charging about 2.5 times the cost of a Standard Edition machine with a reasonable amount of base memory and disk for a similarly configured box running Enterprise Edition.

The table shows that the i5s offer roughly twice the performance per processor as the iSeries machines they replace. For a machine in the 25,000 TPM performance range, a Model 520 with a single 1.5 GHz Power5 processor with 2 GB of main memory and 70 GB of disk costs about $42,530 running Standard Edition and $112,530 running Enterprise Edition. This represents a 20 percent improvement in bang for the buck on Standard Edition compared to a similarly configured iSeries Model 810 with about the same performance. IBM chopped the price of Enterprise Edition significantly on the Model 520, which yielded a 50 percent improvement in price performance.

For larger machines in the 50,000 TPM bands, I compared the i5 Model 570 with two 1.65 GHz processors activated and 4 GB of main memory to a four-way iSeries Model 825 using 1.1 GHz Power4 processors. The i5 offered a 41 percent improvement in price performance running Standard Edition and a 36 percent improvement running Enterprise Edition. FYI: It costs $4,400 to activate a Power5 core on the Model 570s, and $45,000 to activate OS/400 on each core. This is a significant factor in the cost of a configured i5 server with more than the base processors activated. However, for Linux workloads, those extra processors are significantly cheaper. Only $4,500 per core plus the few grand that Red Hat and Novell charge for the respective Linux support contracts.

On the high-end midrange boxes with four Power5 cores activated and over 100,000 TPM of raw performance, the cost of a unit of work on a Standard Edition machine has dropped by 53 percent, and it has dropped by 57 percent on an Enterprise Edition machine. The pricing for this four-way Model 570 box is a little more attractive than on the two way box and close to the pricing IBM is charging on the regular uniprocessor Model 520. There is still a bell curve in the power costs, as has been true since 1988, but the curve is a lot flatter with the i5s than it has even been. IBM, it seems, is trying to keep the cost of OS/400 processing power more fair across the product line, which means Big Blue has finally figured out that its core midrange customers, who have traditionally bought the small 9406 boxes, do not want to pay a bigger premium for processing capacity than entry or high-end OS/400 server customers, who have received attractive price breaks for competitive reasons. Moreover, it means that as customers enter the i5 product line at one point, they are not surprised by a sudden bump in the cost of processing capacity.

Of course, we have not seen the i5 Model 550 four-way server yet, nor have we seen the larger Model 570s (which will span 16 processor cores eventually) and the 64-way Model 590s. Pricing for a unit of processing capacity could go all wobbly again. One thing I know for sure: I’ll be checking.