Lining Up Power7+ Versus Power8 Machines With IBM i
May 27, 2014 Timothy Prickett Morgan
I checked my math and feeds and speeds twice, and I did it again just to be sure. And I would be the first to admit that after many weeks of traveling, most recently at IBM‘s Edge2014 conference in Las Vegas where I got to raise a few pints with my steady IBM i compatriot Dan Burger and some good people at IBM, I might be so tired that I didn’t do the math right. But I think I got it right, and I think that at least as far as base configurations are concerned, the Power7+ machines from last year are a better deal by some measures than the new Power8 machines. In others, the Power8 whips ’em.
Yeah, I know. That doesn’t sound right. But it is true. If you want a lower entry point price, the Power7+ machines are better. The Power8-based Power S814 single-socket machine has a higher entry price tag, but slightly better bang for the buck. And the Power S824 offers a little bit better bang for the buck than the Power 740+ it replaces in the line, and it comes in an IBM i P10 software tier instead of a P20 tier like the Power 740+ does.
I expected for IBM to charge a premium compared to Linux-only Power8 machines, and a less steep premium on the Power8 system that can run AIX or Linux but not IBM i. This is the kind of staggered pricing IBM has traditionally used to try to extract the maximum profits from its various installed bases when the iron was somewhat different–back in the late 1990s and early 2000s–and which resurfaced soon after the systems were literally converged in 2010 to one single product line. For a short period of time, before the Linux-only PowerLinux machines came out, customers using IBM i paid the same hardware prices for compute and storage as those buying systems for AIX and Linux.
To reckon the cost and bang for the buck of the entry Power7+ and Power8 machines, I went to the stack of documents I keep laying around my desk and ginned up tables showing the base configurations from IBM’s online store. Here is what the four entry Power7+ machines and the two entry Power8 machines that are allowed to run IBM i look like:
It is immediately obvious that IBM offered different form factors and more processor options with the Power7+ machines, and the Power7 machines before them, which shared the same enclosures. IBM is simplifying its product line with the Power8 machines, but will very likely add at least one or two models with a four-core processor aimed at the P05 software tier for IBM i workloads. (IBM has made no promises on this yet, and I will discuss that in a future story.) You can tell that the entry prices for the smaller Power 710+ (which comes in a 2U enclosure) and the Power 720+ (which comes in a 4U enclosure) are considerably lower than for the Power8 machines. But entry price is not everything, you have to look at bang for the buck. So here is what it looks like when you add the Commercial Performance Workload (CPW) ratings for the machines and do a little division:
I did not bring in the two Linux-only boxes and the one AIX-Linux box into these tables, which would no doubt show, with the estimated CPW ratings for these machines, that the cost per compute would be considerably lower even still should IBM i be allowed to run on them.
The two Power8 machines that run IBM i, the single-socket Power S814 and the two-socket Power S824, are both in the P10 software group, and this chart below shows only P10-class machines in the Power7+ and Power8 families so you can get a better sense of it:
The Power 710+ machines on the far left of this chart are not really suitable for IBM i because they don’t have very much expansion room, and going to this machine means being very constrained in terms of disk and flash and other peripherals. When you look at it this way, then the Power 720 machines (8202-E4D2 and 8202-E4D3) are actually a little more expensive per CPW than the two models of the Power S814 (that is models 8282-41A1 and 8282-41A2).
The price reductions inherent in the Power S824 are real, not just because of the lower software bill, which is a huge thing, but also because the hardware has considerably more oomph for about the same price or a lower price for around the same performance. It all comes down to cases, as you can see from analyzing the performance and pricing in the tables and chart above. It is not a simple matter to say the Power8 machines universally beat the Power7+ machines. In most cases, you can find a better deal if you sift through the options, but it is not cut and dried where you can say every configuration is less expensive by 25 to 30 percent.
Remember, of course, this is base hardware pricing, not configured systems with operating systems and hypervisors installed. The software bill will radically change these relative comparisons, I am sure. And I am working to put the monster tables together to show that. Stay tuned.