Entry Power7+ Servers: Those 720+ and 740+ Boxes Are Gonna Cost Ya
March 4, 2013 Timothy Prickett Morgan
Let me give you a piece of advice. If your IBM i workloads are such that they are compute intensive but not data intensive, and you can cram all of the peripherals you need into a 2U rack server, such as the chassis used with the new Power 710+ and Power 730+ servers, then you most assuredly should do so. Because the expandability inherent in the 4U rack or tower enclosures used with the Power 720+ and Power 740+ servers, including the ability to hang lots of external disk off the box, are going to cost you.
I have come to this conclusion after pouring over all of the feeds and speeds and pricing for the four new entry machines in the Power7+ server lineup, which debuted on February 5 and which started shipping on February 20.
It is perhaps not a coincidence that the Power 720-class server is the most popular one in use among IBM i shops and that the Power 740-class server is the next machine up the line that the Power 720 customer would upgrade into after moving up through the Power 720 upgrades, whether or not the machine was using a Power7 or Power7+ processor. Unlike in days gone by, when AS/400 and iSeries shops paid extra for hardware identical to the RS/6000 or pSeries line just because they ran OS/400 or i5/OS and even more if they wanted to run green-screen software, in this case IBM has some sort of justification for charging more for Power 720+ and Power 740+ machines compared to their Power 710+ and Power 730+ brethren. The Power 720+ and Power 740+, like their predecessors using the Power7 processor, have one or two GX++ slots, which are a modified InfiniBand adapter on the processor itself that allows remote I/O to plug directly into the processor complex. IBM has been doing this forever–long before Intel’s decision to put a PCI-Express 3.0 port on a Xeon E5 chip last year–and it is one of the reasons why the Power Systems line is still worth a premium. The ability to hang lots of I/O right off the processor is very useful, particularly for online transaction processing machines that have lots of I/O and data storage needs.
But as IBM has slashed prices on the Power 710+ and Power 730+ machines to position them better against Intel’s Xeon E5 iron in similar 2U rack enclosures, it has not kept the cost of processing capacity on the Power 720+ and Power 740+ machines in lockstep. The cost of that expanded main memory and disk capacity, as well as the ability to have more I/O slots and more remote I/O drawers, expresses itself in significantly higher processor card and Power7+ core activation prices once you go beyond the base processor card with four cores (which run at 3.6 GHz in both machines) in either a Power 710+ or Power 720+. If you step up to the six-core or eight-core variants, you pay a lot more for processing. It is not like you are getting nothing for something. In the case of the Power 710+, there is a single GX++ slot, but you cannot hang 12X I/O loops or remote I/O drawers off of it, officially. (I have a hard time believing it can’t be done.)
The same holds true when comparing the Power 730+ to the Power 740+. The latter box is twice as high and has more peripheral slots (five full-height PCI-Express 2.0 x8 slots, with an optional four x8 low-profile slots off a riser card, just like the Power 720+) than the Power 710+ or the Power 730+, which has only five PCI-Express 2.0 low-profile slots. The Power 710+ can’t have 12X I/O drawers and the Power 730+ can only support two drawers off its two GX++ ports. The Power 720+ has two GX++ ports and can host one 12X I/O loop and two drawers, while the Power 740+ has two loops and can do four I/O drawers. The upshot is that the Power 720+ can have up to 380 disks hanging off it, and the Power 740 can have up to 416. But, again, if you can get by with SAS disk enclosures hanging off the peripheral cards, then the Power 710+ can hold 102 drives in the system unit and EXP24S drawers, and if you are a Power 520 or Power 720 customer looking to move up, I strongly suggest you take a hard look at the Power 710.
Look at the difference in pricing for the raw processor capacity across the entry Power7+ server lineup:
Again, you get more I/O and memory expandability in the Power 720+ and Power 740+, but you are going to pay for that potential even if you never use it as expressed in the higher processor card and processor core activation prices.
In the chart above, I show the different processor options and the maximum number of cores at each speed. The price is the cost of getting that particular processor feature card and activating the number of cores on each card as show across the top–4, 6, 8, 12, or 16. The performance is reckoned in Commercial Performance Workload (CPW) units, as has been the case for OS/400 and IBM i workloads since Big Blue retired the RAMP-C ratings a zillion years ago. The cost per CPW is just for the processor feature card, not for any other part of the system.
CPU pricing is one thing, you say, but what effect does that have on overall system pricing. Well, quite a bit, as you will see.
To reckon this, I ginned up small, medium, large, and extra large configurations, which span what I think is the typical range of CPU and memory capacity needs over the life of one of these four entry Power7+ machines. I tried to get the configurations for the Power 710+ and Power 720+ as close as possible and ditto for the Power 730+ and Power 740+ machines, with the idea that you might need to make comparisons for possible future upgrades between boxes as well as within them. I think I got the configurations more or less right, since the cost of the fattest single-socket box matches the skinniest two-socket box, and lo and behold, so does the configuration of memory, disk, and processing capacity within a small wiggle.
The upshot is that for Power 710+ and Power 720+ machines with two or four cores activated on a four-core processor card, the pricing is nearly identical and the performance is identical because both machines are using the same 3.6 GHz Power7+ cores. Take a gander:
In this table, I have the price of the base system plus the processor features and core activations shown. Then, I added memory, a RAID 5 disk controller, enough 856 GB 10K RPM disks to give it a reasonable amount of base capacity, a storage backplane for those disks, a quad-port Gigabit Ethernet adapter, and a power supply. As you can see, these machines do not cost a mere $6,000. And by the way, neither do X86-based servers when you load them up. (Be patient, I will get to the comparisons.)
As you can see from the second table, you pay a slight premium at the system level for a Power 720+ compared to a Power 710+, but no big deal. It is a few percent.
Oh, but once you step up the processor to a six-core or eight-core Power7+ chip, the ones used in the Power 710+ provide more performance and cost roughly a quarter as much. Yup, that seems fishy to me, particularly if you will never get around to installing the maximum of 512GB of main memory in a fat Power 720+ machine. The premium is 19 percent for a large Power 720+ and 41 percent for an extra large Power 720+, and if you do the price/performance calculation, the premium is more like 39 percent and 62 percent, respectively. This is at the systems level. And then, when you factor in the fact that IBM is more likely to discount AIX and Linux customers on the Power 710+ and not discount as much on the Power 710+ or the Power 720+, particularly on software but definitely on hardware, the gap between AIX on a Power 710+ and IBM i on a Power 720+ opens up quite a bit further.
IBM i people, it is high time for you to acquire a collection of Microsoft and Red Hat coffee mugs and make sure you serve your IBM rep and business partner them when they come in to talk about their bid for your new iron. I would never suggest you actually move away from IBM i, but you need to work the deal a bit here.
The premium that you will pay with the Power 740+ compared to the Power 730+ for equivalent capacity and performance is even higher than the gap between the Power 720+ and the Power 710+, as you can see in the chart above. With like-for-like system configurations, a Power 740+ will cost anywhere from 47 to 90 percent more (the gap widens as you make bigger machines, and only because of the difference in CPU costs), and when you do the bang for the buck calculations, the Power 740+ costs anywhere from 56 to 86 percent more per unit of Commercial Performance Workload (CPW) of capacity. This is at the system level, remember.
Here are some things I noticed going through the configurations and pricing information that might be helpful. Pricing on the six-core Power7+ chip running at 4.2 GHz used in the Power 730+ machine is pretty aggressive, and on a per-CPW basis, the eight-core Power7+ running at 3.6 GHz in the Power 730+ is even more aggressive. It looks like IBM is having trouble getting Power7+ chips that have all eight cores running and that also clock at higher speeds. If you can get by on the lower speeds, the processors are cheaper. But remember, you are paying for IBM i on a per-core basis, so you may spend more money this way if you are not careful. Watch out for six-core and eight-core processors on the Power 720+ and Power 740+ machines. They are very pricey indeed compared to the rest of the options in the Power7+ entry server lineup.
Next week, I’ll take a look at what processing capacity on these entry Power7+ machines cost when you add IBM i and Software Maintenance to the mix, and we’ll also take a gander at how IBM thinks the new entry machines stack up against predecessors. I will then do the same set of comparisons for the Power 750+ and Power 760+ servers in the coming weeks.