Can My Power 520 Run IBM i 7.1, And Do It Well?

Published: September 17, 2012

by Timothy Prickett Morgan

We get a lot of questions here at IT Jungle, and we do our best to try to get you answers. With new Power7+ servers coming soon, IBM is getting ready to mothball Power6+ processor cards early next year (as we report on elsewhere in this issue), and i5/OS V5R4 support being ceased on September 30 next year, customers with older Power5 through Power6+ machinery have a lot to think about.

One customer who contacted us recently is willing to ponder the jump from i5/OS V5R4 to IBM i 7.1, but none of the documentation that either he or I could find out there on the Intertubes gave us any sense of how well or poorly IBM i 7.1 would run on any specific machine.

As is often the case with IBM midrange shops, the customer who contacted me was blissfully unware of the configuration on the machine he was using to run the business. (Isn't it great that you don't have to care? Well, right up to the moment when you do, of course. . . .) It turns out, after much going through system configuration files in V5R4, this customer learned that the machine in question is a Power 520 Value Edition box with a single Power5+ processor (feature 7350) running at 1.9 GHz. This machine has a mere 2 GB of main memory and four 32.5 GB disk drives (10K RPM) that are 58 percent full across the RAID 5 group.

The first question this user posed is: Can this machine run IBM i 7.1? That's easy enough. Yes, technically speaking, any vintage box using Power5, Power5+, Power6, or Power6+ processors, as well as new boxes using Power7 processors and future Power7+ machines will run IBM i 7.1.

But, the next question is a little more difficult to get at: Will this Power 520 Value Edition run IBM i 7.1 well? The history of operating systems gives us the answer to this, and if you have ever upgraded your PC or a server, you know this is always true. Any new operating system is tuned to run on new iron and generally runs slower on older gear then the operating system that was tuned to run on that older gear years earlier. What you give up in performance you gain in functionality.

That's a rule of thumb, but that is not a complete answer. And to get one, I went to Doug Bidwell, president and chief propellerhead at IBM midrange business partner DLB Associates. And neither he nor I are providing any kind of guarantee that after the upgrade there will be enough performance, because you can't do that unless you see a machine's particular workloads running before and after the upgrade. Given that, here's what Bidwell said:

"I think that's what I have here in my garage. It runs up to IBM i 7.1, but you have to remember that with each level you jump up, you lose 10 to 15 percent of your performance. You can offset that somewhat by adding memory. Tell them to bump up to 8 GB and they can run for long time. Not fast, but, fast enough. . . ."

Which brings me to my next point, and it is one of the first things I learned as a cub reporter and amateur system performance analyst when The Four Hundred was first published back in the late 1980s. Memory and disk I/O often matter more than raw processing capacity. Using IBM's own Performance Tools/400 performance estimation tools, I could show time and again that adding memory and a few more disk drives to an existing system yielded as much performance as a move to a base configuration of a newer system with a higher RAMP-C or CPW performance rating.

That Power 520 machine dates from January 2006 and has one core and was rated at 600 CPWs of raw computing performance and has 30 CPWs of 5250 green-screen processing capacity, which ain't a lot. But the machine also had a feature called Accelerator for System i5, as as you can see from my write up back in February 2006, which gave the raw CPW side of the machine a boost from 600 CPWs to 3,100 CPWs. If this customer's workloads are not banging the green-screens particularly hard, then the Accelerator upgrade to boost CPWs might be the way to go. Back in 2006, this Accelerator feature cost $13,499 against a base configuration price of $8,200 for the Power 520 Value Edition, but that is a completely bogus price six and three-quarter years later. If IBM will give it to the customer a reasonable price, it should be thrilled to have the customer moving ahead to IBM i 7.1.

With the Power 520 Value Edition having eight memory slots, and this machine above in question sporting 512 MB memory sticks in four of the slots, it is possible that you could buy four feature 4474 memory sticks on the open market. These have 2GB of capacity and originally listed for $1,160 a pop. I have no idea what they cost on the open market today, but Midland Information Systems, a reseller in Apopka, Florida, is selling these modules here. You can also plunk 4 GB modules in the machines, and could boost the memory to 8 GB with only two sticks as well. Flagship Technologies, a dealer located in Hamel, Minnesota, is selling the 2 GB modules for the Power 520 for $350 a pop and has 11 in stock as we go to press. So that memory upgrade might cost you $1,400 in this case, and you end up with 8 GB of new memory and 2 GB of existing memory.

But, just to make things complicated, there's a System i 9407-515 at Flagship with the same 1.9 GHz Power5+ processor and in the same P05 processor group as the Power 520 Value Edition that this customer has. With 4 GB of memory and four disks with 280 GB of capacity, this Power 515 machine is rated at 800 CPWs of oomph for either server or green-screen workloads (they have the same rating unlike older boxes), you get a more capable machine for $2,000. Add another $700 to add another 4 GB of memory, and now for $2,700 you have a box that probably has a lot more oomph than the existing machine, that will run IBM i better than the existing box, and you get to keep the old box around for development after you are sure this second-hand box is working properly running workloads and IBM i 7.1.

It would be nice to have shiny new Power7 iron with IBM i 7.1 installed, but this is probably beyond the budget of most shops using vintage Power 520 gear.

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