IBM to Mothball a Whole Bunch of Stuff with Power7

Published: September 28, 2009

by Timothy Prickett Morgan

Apropos of nothing last week, I was ruminating about the planning that AS/400, iSeries, and System i shops need to do as they prepare for the Power7 generation of servers running a patched i 6.1 or the new i 7.1 operating system. IBM has been slowly lifting the veil on the Power7 chips throughout the summer, but hasn't said much about the systems that will use them.

Yes, as The Four Hundred reported back in August, IBM has guaranteed upgrade paths for customers with Power 570 servers (with either Power6 or Power6+ chips) or Power 595 servers (which only shipped with Power6 chips). And there have been a few hints about how some older technologies used in iSeries and System i boxes might be mothballed, but this statement of direction was all i shops had to steer by, unless they play golf with the top brass in the Power Systems division.

In the wake of my story last week, an intrepid reader showed me that in late August, IBM quietly added a second statement of direction relating to the Power Systems i platform that spells out a few more planning issues that i shops need to ponder.

Let's go through this second statement of direction and planning statement for the Power7 transition.

IBM is being explicit--sort of--about where Power5 and Power5+ customers stand. The company says that any upgrades it is planning that preserve serial numbers as customers move to Power7 chips will have Power6-based servers as their starting point. IBM meant to say Power6 or Power6+, but as you know, IBM never really copped to launching Power6+ processors in some Power Systems boxes in October 2008 with a refresh in others in April of this year. And if IBM was speaking in plain English--well, American at least--what this planning statement would say is this: Customers using a Power5 or Power5+ server will not be able to upgrade to Power7 machines in a manner that preserves serial numbers; they will have to upgrade first to a Power6 or Power6+ box and then do a second upgrade to a Power7 machine.

This serial number thing is important for the accountants and the tax man. (If you don't preserve the serial number, you have to write off the full value of the initial asset at the time of the upgrade.)

Notice how IBM did not say it would not offer upgrades from Power5 or Power5+ machines to Power7 iron? It doesn't mean there isn't an upgrade path available. It just means you will have to write off the value of the older gear. In that case, you might as well just get a new box and find a new use for the old one, perhaps on the second-hand market. Such as it is.

IBM says that the current I/O drawers with the 12X I/O links (yes, this is really a gussied up version of InfiniBand) will be able to be plugged into Power7 machines. This stands to reason, since InfiniBand is backward compatible, just like Ethernet and Fibre Channel (which was the basis of the Remote I/O, or RIO, external peripheral drawers). The older High Speed Link (HSL) and RIO drawers will not link into Power7 boxes. So if you have the older HSL/RIO drawers, IBM is advising that you upgrade before too long.

What I find mysterious about this is that IBM has not said anything about if it plans to use quad-data rate InfiniBand (40 Gb/sec) or 10 Gigabit or even 40 Gigabit Ethernet as the basis for the links between servers and I/O with Power7 machinery. The fact that the Power6 generation of I/O drawers will work leads me to believe that Big Blue will just move up to QDR InfiniBand and not try to transition to a faster Ethernet as a kind of converged storage backbone. Everyone else in the industry is heading in that direction, by the way. But it is way early in the curve, and InfiniBand already has a lot of stuff (such as lossless data transmission) that Ethernet is just now getting with the evolving (but nearly done) Converged Enhanced Ethernet (CEE) and Fibre Channel over Ethernet (FCoE) standards. Fibre Channel over InfiniBand has worked for years. Witness the 12X I/O drawers, for one.

I think IBM will have to move to QDR InfiniBand for I/O drawer links for a simple reason. The PCI-Express 2.0 peripheral slot standard has a peak data rate of 40 Gigabits/sec. If you don't have a faster and wider network pipe, the I/O is going to flood it. And when the I/O pipes are flooded, expensive multicore processors like Power7 chips spin their cycles and do not work. As a wise man once said, all computers wait at precisely the same speed. . . . And waiting is the one thing system engineers have to design out of the box.

This planning document also warns that Power6 machines will be the last boxes to support SCSI drives with 36 GB or smaller capacities and SCSI drives that spin at 10K RPM or less. Ditto for quarter-inch tape cartridges; Power6 machines are the end of the line for this venerable tape tech. And say sayonara to I/O Processor (IOP) and IOP-based PCI adapter cards. Look at the items in the list and see that twinax workstation controllers, and hence twinax dumb tubes and printers, will need some kind of third-party conversion box to talk to Power7 machinery, and Integrated xSeries Series x86 co-processors and a number of other adapters--well, wave goodbye. If you are using these drives, tapes, and IOP adapters and you want to move to Power7 gear next year, it is like money and death: you can't take it with you.

This is probably by no means all of the technology issues that will affect a move to Power7 technology. But it is food for thought--and planning.

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