IBM i Gets The Big Power9 Iron, But Not The Midrange
August 15, 2018 Timothy Prickett Morgan
First of all, let me apologize for not getting to this story last week, but I had a bunch of personal stuff going on and frankly, it is still going on. To eliminate the mystery, I will tell you the big part, which is that I was preparing to get married, then got married, and then tried to take a short honeymoon out in the mountains, and I did not expect for IBM to try to announce the last of the Power9 servers smack dab in the middle of all that.
But on August 7, IBM did just that. For now, I am going to give you the highlights of the “Zeppelin” Power E950 and the “Fleetwood/Mack” Power E980 machines, which are pretty much coming to market much as I have been expecting and well within the third quarter 2018 expected delivery date that IBM had set late last year. I happen to think that all of the Power9 machines are many months later coming out than Big Blue had originally planned, but Intel, AMD, and Cavium have been late with their server processors, too, so there is no lost ground from a competitive standpoint – unless you think about all of the gained ground IBM could have made if the full line was available last summer. Maybe I am too optimistic; I have been accused of that from time to time.
The Power E950 machine maybe should have been ironically code-named “Survivor,” because there is no Eye Of The Tiger. As was the case with the Power8-based Power E850 and Power E850C, the IBM i platform is not made available on the Power9-based Power E950, both of which are the quad-socket servers in their respective 2014 and 2018 lineups. I have grumbled a bit about the fact that there is no midrange server in the IBM i midrange – which seems impossible, I know – but we all know that the vast majority of IBM i shops have maybe one, two, or four cores on a single socket server, and even the biggest shops, provided they do not need a lot of memory or I/O, try to get by on a two-socket box in the Power S824 or now the Power S924 class. I will get into this separately, but I think this is more about how Big Blue is packaging the IBM i platform and the nature of workload growth on the system than it is about not needing an affordable and powerful four-socket machine. Suffice it to say for now that a Power E950 with a reasonable IBM i software tier designation is precisely the kind of machine that could sell lot hotcakes if positioned correctly. But alas, the Power E950 will only support AIX and Linux, not IBM i.
The much larger Power E980 systems, which gang up from two to four of a slightly different four-way system, will run the IBM i operating system and database mashup as well as AIX and Linux. The main reason for skipping the Power E850, according to Steve Sibley, product offering manager for the Cognitive Systems division at IBM, is that the Centaur DIMMs, which have the memory buffer chip on each memory stick instead of on a memory riser card like the Power E950s, have four to five times the reliability of the versions of the cards that have the Centaur separately on the riser. This may not make a big difference on machines with modest memory or running clustered workloads, but on enterprise OLTP workloads that are moving money, higher memory availability and memory throughput matters more than lower cost and IBM steers these customers up to smaller configurations of the more resilient machines. With 64 TB of memory, the chance of a memory bit flipping or a memory chip failing is pretty significant, and the CDIMMs can protect against these errors. The Power E980 has a lot more I/O capacity, too, and is itself more resilient. And to IBM’s way of thinking, a four-way Power E950 would be in the same P30 software tier as a four-way Power E950, so what is the big deal of having to buy an entry Power E980?
I think my whole argument is that a Power E950 should cost a lot less than an entry Power E980, and I will have fun showing why.
Both the Power E950 and the Power E980 use the Centaur buffered memory, which is actually a good thing even if it is inconvenient in some ways, and to our thinking, the way that it is done in the Power E950 is the right way. The Power E950 puts 16 regular DDR4 memory sticks of varying capacity and running at only a modest 1.6 GHz (so it is cheaper and dissipates less heat than DDR4 sticks that clock higher at 2.4 GHz or 2.8 GHz). By using Centaur buffer chips, IBM can hang twice as much memory off of the eight memory controllers on the 12-core “Cumulus” Power9 chips, which are aimed at NUMA boxes that are explicitly created to provide more memory capacity, more memory bandwidth, and more socket scalability than the standard one-socket or two-socket Power9 machines, which IBM has been rolling out through the spring and which are based on the 24-core “Nimbus” Power9 chips that do not support buffered memory and do not need it to remain competitive with X86 and Arm server chip alternatives. In any event, there are four Centaur buffers per memory riser card on the Power E950, fanning out to 16 standard DIMMs, yielding a whopping 16 TB of peak main memory capacity and 980 GB/sec of memory bandwidth on a fully loaded system using 128 GB memory sticks.
The Power E980 nodes do not use standard DDR4 DIMMs, but rather IBM’s own CDIMMs with their stacked memory, and each node only holds 32 memory slots for the same total of 128 slots in a system. The Power E850 does this in one node, and the Power E980 does it across four nodes to reach that maximum. But here is the difference. The CDIMMs are now available in capacities of up to 512 GB each, so maximum memory capacity is now 64 TB, compared to a maximum of 32 TB with the Power E880. The other big difference is that the Power E980 can accept CDIMM memory cards that were used in the Power E870 and Power E880 machines, so customers doing serial number upgrades on the boxes can literally move over their 64 GB, 128 GB, or 256 GB memory cards. We don’t think a lot of customers will be buying Power E980 machines with the full-on 64 TB and 192 cores in a single shared memory space, not given the cost of memory these days for sure. But we do think that, over time, customers will be focused more on the memory hierarchy than the raw compute of their systems.
The Power E950 will be generally available this week on August 17, but that doesn’t matter much to IBM i shops because Big Blue is not supporting IBM i on the machines. Power E980 systems with a single or a pair of nodes will be available on September 21, and machines with three or four nodes will be available on November 16. Upgrades from Power E870 and Power E880 systems to the new Power E980 will also be available on November 16. We do not yet have all of the feeds and speeds and pricing, but are gathering up the data now and will be doing the usual deep dive. Hang with us.