IBM i Competes with AIX/Oracle on Power 720s, Gets Beat on 750s

October 25, 2010 Timothy Prickett Morgan

Despite all the changes in the Power Systems lineup with the Power7 processors this year and a slew of entry and midrange servers, the most likely servers that IBM i shops are likely to buy, for a whole cornucopia of different colored reasons, are the Power 720 or 750 with a modest number of relatively low-speed processors. The good news for Power 720 shops is that the i 7.1 software stack, which includes an integrated DB2 database, is absolutely competitive with combination of IBM‘s AIX Unix variant and the most appropriate 11g relational database from Oracle.

The bad news–and something that I have railed about time and again to Big Blue–is that the Power 750’s i 6.1 and 7.1 licenses are too expensive. IBM is pricing the i 6.1 and 7.1 against an enterprise-level license when the feeds and speeds of the machines (at least as far as Oracle is concerned) warrant a cheapo or standard license.

I already showed you how the Power 750’s stacked up against their predecessors back in August, and did similar comparisons between the Power 720 and its predecessors a month ago. Both machines do alright compared to their forbears, but they are not just competing with history, but also with current events in the server racket. To give you a broader sense of what raw processing capacity (just processor feature cards and core activations), I walked you through how each feature for which IBM has provided a Commercial Processing Workload (CPW) benchmark test rating stacks up with all the others in the Power7 product line. Then, the following week, I burned the raw processing cards with i 7.1 operating system and Software Maintenance for the processor cores activated on the processor features. (These latter two comparisons did not include the cost of a server or rack chassis, memory, disks, or other peripherals, unlike the other comparisons.)

This week, I am taking the configurations of the Power 720 and 750 that I used to compare these new machines to their predecessors in the Power 520, 525, and 550 lines, and reconfiguring them to run AIX 7.1 and the Oracle 11g database. After loading up the new software stack on the same iron, I do two comparisons: one assuming the online transaction processing power running the AIX-Oracle combo doesn’t change at all compared to i 7.1 and then I use the Relative Performance (rPerf) metrics given out by IBM for AIX shops to measure relative performance and reckon the estimated TPC-C transactions per minute (TPM) throughput of the system. Historically, as I have said many times, TPC-C TPM is equal to CPW times 9.95, while in recent years TPC-C is roughly rPerf times 11,400. IBM has been showing an increasingly large gap in OLTP performance between OS/400 and i machines compared to AIX boxes in recent years, and I happen to think that this has more to do with benchmarketing than actual inherent performance differences on entry and midrange servers. (i5/OS V5R4, i 6.1, and i 7.1 certainly do have threading limitations on larger Power-based servers, and that will affect database throughput without question.) I think IBM has been tuning the living daylights out of AIX performance on the TPC-C tests, and Big Blue doesn’t run TPC-C benchmarks on the IBM i stack any more, so it is hard to be sure.

I give you the performance metrics so you can see them, but I think that it is probably best to think about it in terms of how many OLTP users are going to be sitting on the system. That’s why I add specific numbers of users to the i 7.1 and AIX-Oracle configurations of the Power 720 and 750 shown in this week’s TPM monster performance anxiety table (patent-pending). These configured machines include a reasonable amount of base memory, some disks with RAID 5 data protection, and an LTO tape drive for archiving data. I have used IBM’s Express configurations as a baseline.

All the data is in there for you to play with, but take a gander at how the Power 720 machines look with one or two cores activated with the software stacks and an increasing number of users on the boxes:

On the Power 720 using the 3 GHz processors and only scaling to four cores, the i 7.1 license is very cheap at $2,245, including five users. If you want to add users, it costs you $250 a pop. Oracle sells a version of the 11g database called Standard Edition One that is meant to scale across two socket servers, and this one is sold either on a per-user basis at $180 a pop or on a per-socket basis at $5,800 each. Obviously, for a low number of users on a one or two socket machine (regardless of core counts), it is cheaper to pay on a per-user basis instead of a per-socket basis, and conversely, for a large number of users, it is cheaper to buy the per-socket licenses. I have done this in each case, opting for the cheapest Oracle 11g option on any given number of users and configurations.

On the Power 720 machine, AIX costs $1,200 per core for the Express Edition, $2,000 per core for the Standard Edition, and $3,160 per core for the Enterprise Edition. AIX Express can only span a maximum of four cores in a single operating system image and can only address a maximum of 8 GB of main memory per core. AIX Standard can span up to 64 cores and has no memory limitations, and AIX Enterprise can span up to 256 cores and includes workload partition manager and live migration of AIX instances. On the Power 750, AIX is more expensive–twice as expensive per core, in fact. IBM i 7.1 on the Power 750 costs $40,000 per core, which is way too expensive considering that Oracle Standard Edition (which can span across the four sockets in the Power 750) costs $17,500 per socket. Oracle only uses per-core scaling factors on the Enterprise Edition of its database, which costs $47,500 per core after adjusting by a scaling factor that ranges from 0.25 to 1.0. The scaling factor is 1.0 on any Power6 or Power7 server when it comes to 11g Enterprise Edition, which means, in theory, it would cost $12,160,000 to put Oracle 11g EE on a fully loaded Power 795, with another $2,675,200 due for the first year of support.

Yeah, right.

Anyway, as you can see from the table and from the chart above, the i 7.1 stack competes just fine with the AIX and Oracle SEO combination, at least on a per-user basis, on the small Power 720s. It is almost like someone did the math ahead of time and made sure the entry Power 720 setups with a couple of cores activated–the most likely machine an IBM i shop will buy, regardless of the other blade and entry rack server choices. This is the correct level of pricing–absolutely competitive, no ifs, ands, or buts. And with this being the case, it would be useful if IBM would actually get off its lazy keister and run some actual OLTP tests showing that the Power 720 can deliver good bang for the buck running i 7.1 compared to Unix systems.

On two-core systems, the price difference starts to drift because of the difference between $180 (Oracle SEO) and $250 per user (i 7.1), and the answer as far as I am concerned is for IBM to drop the price per user to $180 a pop or whatever it takes to beat the AIX or Oracle combination. The rest of the pricing is fine. (At least until we look at Windows boxes, and perhaps I will be freaking out. But let’s not get ahead of ourselves here. I have not run the numbers yet.)

With the Power 720, interactive 5250 processing capacity is built into the box, but on the Power 750, in addition to paying a much higher licensing fee per core, you also have to buy access to green-screen processing capacity. In the chart below, I show the OLTP performance of likely entry Power 750 configurations that IBM i shops would go with if they were starting out and leaving some space to grow for later. Here’s how the i 7.1 stack does:

As you can see, the fact that IBM is charging more for i 7.1 really adds up, and the premium for 5250 capacity on the processors makes it even worse. The gap is bad on a two-core Power 750, and it gets even worse on a four-core box. And if you wanted to push it all the way out to a four-socket, 32-core box, the gap would be immense, although I did not do the math for that one even as the cost per user would probably go down a little bit. The other interesting thing you can see is that IBM crammed a lot of cores into the chip and in a four-socket box in part so it could run the cheaper Oracle 11g Standard Edition software but have the kind of scalability in a system that a few years ago might have required an Enterprise Edition license.

Next up, I will see how these Power 720 and Power 750 base machines stack up to some representative X64-based systems using the latest processors from Intel and Advanced Micro Devices.

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