Original URL: http://www.theregister.co.uk/2010/06/17/ibm_aix_7_power/

IBM preps AIX 7.1 for autumn Power7 harvest

Little boxes and big bad iron

By Timothy Prickett Morgan

Posted in Servers, 17th June 2010 23:38 GMT

In the computer racket, it has always been much easier to get new hardware out the door than the software to take advantage of it fully. And so it is with IBM's Power7-based Power Systems machines and its AIX variant of Unix, which is slated for a 7.1 update in the autumn.

AIX 7.1 is expected more or less concurrently with the high-end 256-core Power7 box, presumably to be called the Power 795. This server will sport 1,024 threads and perhaps as much as 8 TB of main memory in a single system image, and the word on the street is that it will also host 640 logical partitions running Big Blue's PowerVM hypervisor.

The word on the street is that IBM is working on high-density memory cards, necessary to balance the large number of cores, and that these - not the operating system and not the multichip modules that will go into the Power 795 machine - are what is holding up the big iron box. Once one part of the system is late, there is no reason to rush out the rest, so the software engineers working on AIX 7.1 are getting a little more time to step on some bugs. Perhaps until late September or early October, when AIX 7.1 is rumored to be shipping.

IBM could, of course, announce it well before then and may be under pressure to launch new Power boxes and AIX 7.1 ahead of plan if Power Systems sales continue to slump in parallel with System z mainframe sales. IBM had originally planned to launch the midrange Power 750, 770, and 780 servers in May of this year (plus a Power 755 variant for HPC customers), but moved them up until February.

The Power 750 and 755 are four-socket machines in a 4U chassis, while the Power 770 and 780 are SMP machines that have from one to four of these 4U chassis, rip out half the processor cards and add in SMP electronics, and then scale as far as eight sockets or 64 cores in a four-chassis system. IBM also pulled the Power Systems 700, 701, and 702 blades into April; the PS700 and PS701 are single-socket blades, and the PS702 snaps two of the PS701s together to make a double-wide, two-socket blade with 16 cores.

The company has three more entry Power Systems in the works - a good guess is a Power 710 and a Power 720 and maybe a Smart Cube appliance server based on the Power 710 box - in addition to the high-end Power 795 box. It is a good guess that IBM has a single-socket entry tower and rack machine as well as a two-socket machine, since these are necessary to keep customers running its proprietary OS/400 and i happy.

While IBM has a number of very large shops running i5/OS V5R4, i 6.1, and now i 7.1, which came out in April, the vast majority of the i base is comprised of SMB customers who have no idea what to do with a 256-core Power Systems machine, and no means of paying for it either. Finally, IBM has also previewed the gigantic Power7 IH node used in the "Blue Waters" petaflops-class supercomputer, which El Reg told you all about last November.

IBM is pretty tight-lipped about what features AIX 7.1 will have, but Satya Sharma, the chief technology officer for the Power Systems division, says that going from a 32-socket machine with 64 cores and 128 threads to one with 256 cores and 1,024 threads (IBM has been very careful to not say how many sockets the big AIX box will have) requires a rethinking of the locking strategy inside the operating system.

Big Blue service pack

IBM is supporting AIX 5.3 and AIX 6.1 on Power7 iron currently through what it calls Technology Level service packs. This is akin to the practice that Red Hat and Novell have of grabbing new features in the Linux kernel and backporting them to prior kernels to give them these features without breaking compatibility.

But just because an AIX release with a Technology Level can run on Power7 iron doesn't mean it can see all of the threads inherent in the processor complex. According to internal IBM documents obtained by El Reg, AIX 5.3 can run on Power7 iron in what IBM calls Power6 mode, which means it can see a maximum of 64 cores and 128 threads. So on a fully loaded Power 770, for instance, with 64 cores, AIX 5.3 will only see half of the 256 threads actually in the box. Ditto for AIX 6.1 at TLs 2, 3, 4, and 5 even the initial AIX 7.1.

AIX 6.1 TL 4 and 5 will have a native Power7 mode that can support 64 cores and 256 threads, which means it can see all the threads inherent in the Plower 770 machine announced in February. But it will take AIX 7.1 running in Power7 mode to span that 256-core, 1,204-thread Power 795 machine.

That's a much better deal that midrange shops running i 6.1 or i 7.1 on the proprietary side of the Power Systems house are getting. For reasons that IBM has never explained, i 6.1 could only span 32 cores and 64 threads in a single system image, but there were patches available on a special bid basis to double that up to 64 cores and 128 threads, the top-end of the Power6 range with the Power 595 server launched in April 2008.

In Power7 mode, i 6.1.1 (a sub-release tuned to the Power7 servers) can support 32 cores and 128 threads, which is half of a Power 770. The new i 7.1 release tops out at the same limits, but there is a special bid version to double it up to the 64 cores and 256 threads that the Power 770 has. If IBM has plans to scale i 7.1 across the full Power 795 with its 256 cores and 1,024 threads, it hasn't told anyone we know about it.

Sharma was not about to divulge a lot about the future AIX 7.1, but he did give some hints about the type of things IBM is working on for future AIX releases in general. As is the case with all other operating systems, kernel fixes require rebooting, and this really annoys customers since it disrupts their data processing on back-end workloads. IBM's software engineers are trying to reduce the time it takes to do updates and patches. "This is an area that is ripe for innovation," says Sharma.

IBM is also trying to make its workload partitions - Big Blue's riff on virtual private servers or containers - more attractive to customers. With the logical partitions, called LPARs in IBMese, implemented by the PowerVM hypervisor, the hardware is abstracted by the hypervisor and each logical partition gets its own copy of AIX, i, or Linux running atop the iron. You have to patch each one of these operating systems, and this is a big pain in the neck. With workload partitions, or WPARs, there's a single AIX kernel and file system and AIX sandboxes are created to isolate workloads that think they have their own copy of AIX, complete with their own security settings. (Solaris 10 containers and BSD Unix jails work the same way).

With WPARs, running AIX workloads can be live migrated around a network of Power Systems machines, which means even when you need to take a machine down to do maintenance, you can get the workload off the box first and then update it. Applications keep running. And that is why Sharma thinks over time, once customers get used to the idea, they will take a shining to WPARs. But right now, Sharma concedes that WPARs are "still not widely deployed."

IBM is also trying to ensure that clusters of AIX machines running the DB2 PureScale database clustering alternative to Oracle's 11g database and Real Application Clusters (RAC) extensions can be managed more like a single system instead of a cluster. Sharma says there is plenty of work being done on "commercial scale out" to mask the complexity of clusters. IBM launched DB2 PureScale in October 2009 as a counter-punch to Oracle Exadata V2 database appliance. In April, the DB2 clustering for AIX was bundled on Power 770 machines as an appliance to create the PureScale Application System, a better defense against Oracle Exadata V2.

The pace of change of AIX development has slowed, as it has for both Hewlett-Packard's HP-UX and now Oracle's Solaris. And the time dilation has been going on for years, as it has been in all operating system platforms. Sharma says that Power Systems shops should look for a new AIX release every three years or so, with Technology Level updates to add new features or adapt to new hardware every six months or so.

"Operating system innovation is not dead," says Sharma, "and it is our intention that AIX will be the last man standing, regardless of what happens to HP-UX or Solaris." ®