Power7+ chips debut in fat IBM midrange systems

Near the top at first, trickling down to smaller boxes next year

Two new servers, and a memory bump in the big bad box

The new Power 770+ server is known by product number 9117-MMD in the IBM catalog, and like its Power 570 and Power 770 predecessors, it's a NUMA machine with one to four server nodes that can be linked with fiber optic cables into a single system through the IBM Power chipset.

Each server node comes in a 4U chassis and has two processor cards, each with two processor sockets, so you can scale the Power 770+ from four to sixteen sockets in a single system image – twice as many sockets as in the Power 770 it replaces.

But that doesn't mean you are going to get twice as many cores in a system.

IBM's Power 770+ server

IBM's Power 770+ server

For the Power 770+ machine, IBM is using Power7+ chips with either three or four cores activated, and not the six or eight cores it had on machines using Power7 processors. Yes, that tells you something about Power7+ chip yields using that 32nm process. And this is one of the reasons why the Power7+ chip is, by IBM's own three-year cadence between chip generations, somewhere in the neighborhood of a year or so late.

A chip that ships on time is the exception, not the rule.

So the Power 770+ machine has the same number of cores as the Power 770, which means it doesn't have as much of a performance boost (in terms of number of cores and threads) as you might have been expecting if you thought that IBM would fill the sockets with chips with six or eight cores.

When yields improve, IBM will no doubt put Power7+ chips with six and eight cores into the Power 770+ systems, and it might even go so far as to double-stuff the sockets for those who really want a lot of cores and threads, and where clock speed doesn't matter so much – but yields will have to improve first.

What you get is a Power 770+ machine with 48 cores running at 4.2GHz with 10MB of L3 cache per core – a 13.5 per cent clock speed boost over the Power7 variant and 2.5X the L3 cache per core – or a machine with 64 cores running at 3.8GHz – a 15.2 per cent clock crank with the same 2.5X L3 cache per core.

If you use IBM's Relative Performance (rPerf) benchmark, a variant of the TPC-C online transaction processing test, to gauge the relative performance of the Power 770+ machine, the old Power 770 with 64 cores running at 3.3GHz was rated at 606.8, while the 64 core version of the Power 770+ is rated at 729.3. That's a 20.2 per cent performance bump.

The Power 770+ has the same 4TB of maximum memory as the updated Power 770' (prime, remember, not a typo) that came out last October, which was twice as much memory as the original Power 770 from 2010. And I happen to believe, by the way, that the Power7+ chips were supposed to go in those Power7' machines from October 2011, but IBM will never confirm that this was indeed the plan.

Each node in the Power 770+ system has six disk bays for a maximum of 1.8TB of storage inside the server skins. Each enclosure has six PCI-Express 2.0 slots for a total of 24 across the fully extended Power 770+ system, which is the same as on the original Power 770 and last year's Power7' box.

The Power Systems machines have a special variant of InfiniBand used for remote I/O drawers, called 12X, that hangs of the GX++ bus on the server, and Sibley says that this bus has better error management and increased bandwidth to host external peripheral drawers. With those 12X I/O drawers hanging off the GX++ bus, the Power 770+ can have a maximum of 184 PCI-Express 2.0 peripheral slots driving sixteen 12X I/O drawers, yielding a maximum of 3PB of internal storage using 900GB 2.5-inch SAS disks.

While IBM is using Power7+ chips with four or five of their cores and a proportional 40MB to 50MB of their cache decommissioned because those part of the circuits have flaws, with the Power 780+ server, also announced today and known as the 9179-MHD in the IBM product catalog, customers are being given the option of either four-core or eight-core variants of the Power7+ chip on system boards that sport two sockets.

On the eight-core variant, the Power7+ chip runs at a slower clock speed than the October Power7' chip, but the four-core version of the Power7+ chip that IBM chose to put into the system runs at a faster clock speed than the Power7' chip it replaces.

The Power 780 that was announced back in 2010 was based on the same iron as the Power 770, with one important difference: the Power 780 had eight-core Power7 chips running at 3.86GHz with all eight cores working, but it also had a Turbo Core mode where customers could deactivate half the cores and let the Power7 cores run at a slightly sprightlier 4.14GHz while at the same time allocating all of the 32MB of L3 cache to the remaining four cores. With the Power 780' (that %$#@! prime again), IBM doubled up the sockets on each system board as the standard configuration while dropping the clock speed down to 3.44GHz across a machine with sixteen sockets using six-core – not eight-core – chips.

Turbo Core mode went the way of all flesh with the Power 780' from October 2011. And "Why?", you ask? Because Oracle counted all the cores on the die – even when they were not on – because customers could change a setting, reboot the Power 780, and in theory get away with paying half as much for their Oracle software licenses. That extra 5.6 per cent of clock speed and double the L3 cache per core was just not worth paying twice the price for Oracle software.

The proper response there would be to charge half as much for AIX and DB2, but what do I know about marketing against Larry Ellison?

The Power 780+ server

The Power 780+ server

There is similarly no Turbo Core mode with the new Power 780+ machine. The system boards with the four-core Power7+ chips run at 4.42GHz, which is 6.8 per cent higher than the Turbo Core mode on a half-cored Power 780 from 2010 running in Turbo Core mode. The Power 780+ has 10MB of cache for each of those cores, compared to 8MB in Turbo Core mode for the original Power 780.

That original Power 780 was rated at 425.5 rPerfs on the AIX relative performance benchmark in Turbo Core mode with 32 cores running at 4.14GHz, and the new Power 780 is rated at 817.1 rPerfs with 64 cores running at 4.4GHz. That's nearly double the performance for double the cores. It's likely that as yields improve, IBM will offer higher clock speeds for the new Power 780+ to improve that performance.

If you want to push throughput instead of single-thread performance, there's an eight-core Power7+ chip available for the Power 780+ system that runs at 3.7GHz and puts 128 cores in a single system image. This machine is rated at 1,380.2 rPerfs, which is a little more than twice the aggregate performance of the original Power 780 using eight-core Power7s.

The Power 780+ has the same peripheral expansion as the Power 770+ above, and both machines offer as many as 20 logical partitions – LPARs in IBMspeak – per core with the PowerVM 2.2.2 hypervisor, which is twice as many VMs as the prior several generations of Power Systems servers could do. A logical partition can scale down to as little as 5 per cent of CPU capacity, according to Sibley.

The speed at which a running LPAR can be teleported from one physical machine to another using PowerVM hypervisors has also been improved by a factor of three on single VM live migrations. (IBM calls this teleporting between physical machines Live Partition Mobility, or LPM.) A Power 770/780 or Power 770'/780' machines could handle eight concurrent LPMs, and the new Power 770+ and 780+ boxes can do sixteen concurrent LPMs.

Both the Power 770+ and Power 780+ machines will be generally available on October 19. AIX 6.1 and 7.1 with appropriate patches will be supported on the machines, as will an update of IBM i 7.1 on first shipment day. A patched version of the earlier IBM i 6.1 release will come out on November 9, and Red Hat Enterprise Linux 6.3 and SUSE Linux Enterprise Server 11 SP2 will also run on these two new boxes.

The venerable AIX 5.3 release will eventually be allowed to run on these machines, but Big Blue must be getting pretty tired of AIX 5.3 about right now. It killed off OS/400 V5R3 years ago, and will be mothballing i5/OS V5R4 next September.

Pricing for the Power 770+ and Power 780+ systems was not available at press time.

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