Big Blue Revives IBM i 7.1 With Power9 Support
November 16, 2020 Timothy Prickett Morgan
We don’t get surprises very often in the Power Systems market, and even fewer in the IBM i sub-market. But last week, we did get a surprise – and it was a pleasant one – as Big Blue decided that it was going to allow for IBM i 7.1, which has long since been removed from marketing and which was just recently given extended extended support through April 2023, to run on selected models of the Power Systems line using Power9 processors.
That IBM would allow for this is remarkable, and it shows the economic and technical difficulties that many companies using IBM i platforms as their mission critical systems are facing during the coronavirus pandemic. In many cases, no matter what their desires, IBM i 7.1 shops cannot move their software ahead. They may have written their own code in a manner that is not compatible with modern releases and have lost their observability templates, the bit of intermediate code that allows for RPG and COBOL applications compiled for earlier Power hardware to be recompiled on the fly the first time they run on newer Power iron. Or perhaps they do not have the source code to their applications so they can recompile, and in many cases that is because their software supplier has gone out of business or they have lost their own. Or, they have been off maintenance with a third party application developer for so long that they cannot afford the back software maintenance fees on their old release so they can get a version of the code that runs on a newer and fully supported release that also works on Power9 iron. Or, they just don’t have money to do hardware upgrades and software upgrades at the same time.
No matter what the issue, push has come to shove and IBM is the one that got shoved a little bit by the push, and the company is relenting by allowing IBM i 7.1 to be loaded on selected Power9 machines. This was revealed last week in announcement letter 120-084, and to be precise, IBM is allowing IBM i 7.1 to run on precisely three machines. The first two are the A and G variants of the Power S922. The A machines were the ones that were announced originally in 2018 and the G machines are the variants with improved PCI-Express 4.0 peripheral I/O and more NVM-Express flash support that were announced in July of this year. The A variants of the Power Systems scale-out machines – what we would simply call entry models with one or two processor sockets – will be withdrawn from marketing on January 29, 2021, as we previously reported. To be super-precise, IBM i 7.1 is available on machines with the 9009-22A and 9009-22G designations. IBM i 7.X is not supported on midrange Power machines anymore – so there was no Power E850, Power E850C, or Power E950 support – and we don’t think IBM is about to change its mind here because it wants to sell used Power E870 and Power E880 iron and new Power E980 iron for those whose workloads don’t fit into a two-socket Power8 or Power9 system. And hence, IBM i 7.1 is now available to run on the Power E980 system, which is model number 9080-M9S if you need to keep track.
Again, the important thing to remember is that IBM i 7.1 was never supported on any Power9 processor until now. IBM i 7.1 came out in 2010 along with the Power7 processors, and was backcast all the way back through Power6+, Power6, and Power5+ and finally to Power5. I know that the data suggests that more recent releases are more popular in the base – check this story culled from the 2020 IBM i Marketplace Survey performed by HelpSystems for the stats by operating system release – but I don’t believe it. I do believe, however, that among the most active customers in the base – meaning those who keep on relatively current hardware and software, who pay for software maintenance to IBM and third parties, who have modern homegrown or third party applications, who read IBM i publications, and who are therefore more likely to take polls – IBM i 7.1 is a relatively small part of the base. But that’s only about a fifth to a quarter of the base. The remaining part of the base is running OS/400 V5R3, i/OS 5.4, IBM i 6.X, and IBM i 7.1.
There are many walls that customers can’t always jump over and get left behind. The big barriers in the past were OS/400 V3R6, OS/400 V5R3, IBM i 6.1, and IBM i 7.1. Each in their turn is like a System/3X generation trapped on the wrong side of progress.
To which I toss out this idea yet again: Why stop there? If the Power9 iron can support all of the PowerPC AS instructions back to 1995, then in theory there is no good reason why some virtualization layer that rides within the PowerVM hypervisor or within a PowerVM logical partition cannot allow a partition to run any OS/400 or IBM i release and its applications. And at this state of the game, it is important to get everyone who is running RPG and COBOL applications against Db2 for i databases to get on modern hardware as a first step in getting their applications modernized. Yielding a bit and supporting IBM i 7.1 on Power9 is a start, but it is just that: Only a start. Let’s move everyone ahead.
There are some catches to the way that the Power9 processors can run IBM i 7.1. The first catch is that the I/O in the machines running the operating system have to be using – you guessed it – the Virtual I/O Server, which is used to virtualize the I/O between the IBM i 7.1 operating system and PowerVM. My presumption is that many of the drivers for Power9 peripherals as well as for the processor itself are not inherent in the IBM i 7.1 operating system and hence this requirement.
IBM also says in the announcement that the IBM i partitions running IBM i 7.1 on the Power9 machinery have to be running in restricted I/O mode. What I have been told by people who know is that the timings with the Power9 machines are not precisely aligned with what IBM i 7.1 expects, which smells a bit funky to me, but which means the I/O has to be slowed down so IBM i 7.1 can support it. The difference in a lot of cases is probably due to the fact that the Power7 servers where IBM i 7.1 first debuted were running a mix of PCI-X and PCI-Express 1.0 slots, and those older Power5 through Power6+ servers that were also able to run this release were using even older peripheral speeds.
We don’t know how much restricted I/O mode affects performance, but even with a substantial overhead or slowing of the peripheral speeds, whatever the Power S922 or Power E980 can do running IBM i 7.1 in a partition will be more oomph than was originally possible on Power7 or earlier iron, or even Power8 iron we figure. IBM’s Knowledge Center entry on restricted I/O mode doesn’t really say much, and certainly doesn’t give any insight into performance implications.
Here is one more catch. On the Power S922 A model, the four-core Power9 processor is not supported, and on the Power S922 G model, the four-core Power9 processor and the one-core Power9 processor are not supported.
And here are a few more. Customers buying new machines have to acquire the Power9 boxes with IBM i 7.3 or IBM i 7.4 and they have to be on Software Maintenance. Having done that, there will now be an option to download IBM i 7.1 keys and partitions can now run IBM i 7.1. You will obviously have to pay for service extension on the IBM i 7.1 licenses as well, which is basically a doubling of Software Maintenance fees.