Last month I wrote a blog post questioning whether the mainframe specialty processors — and in particular the System z Integrated Information Processor (zIIP) and the z Application Assist Processor (zAAP) — can really save a mainframe shop money. It caused a little stir, from vendors and users alike, who contacted me and talked to each other in defense of the zIIP and the zAAP.

My goal of the post wasn’t to say that they can’t save money, because they can. My point was to explain that oftentimes, the savings comes in an indirect manner. In the case of the zIIPs and zAAPs, I said this:

So you might be able to save in software licensing costs, but the processors themselves cost about $100,000. In talking to users, it seemed to me that the benefit of the zIIP and zAAP was more indirect. By taking workloads to those processors, you can free up room on the central processors. That’s what might matter the most.

So instead of having to buy a new mainframe, you can just buy one or two of these zAAPs and/or zIIPs. The real savings comes not from the reduced software licensing costs as much as it does from being able to buy a six-figure specialty engine instead of a new seven- or eight-figure mainframe.

Some took umbrage with that, saying that savings can be realized immediately with software licensing costs, moreso than I was alluding to. Gregg Willhoit, the chief software architect for mainframe software at DataDirect, added that most customers of theirs don’t consider freeing up space on the central processors to be indirect.

“Most people consider deferred capacity upgrades and the ability to grow existing general purpose processors as close to real money as anything else,” he said. “A lot of people don’t mind considering deferred upgrades as immediate savings.”

DataDirect, which makes service-oriented architecture (SOA) software for the mainframe, has been working to get its applications eligible on the zIIP and zAAP. Willhoit said that for some products, such as Shadow z/Services, up to 85% of the work can be offloaded.

There are other software companies out there that are helping customers offload some work to the zIIP and zAAP, including CA, BMC, and Neon Enterprise Software. Hopefully the list will continue to grow.

Another issue at least one person took was how I said growth of the zAAP and zIIP hasn’t been the same as the Integrated Facility for Linux (IFL), which is another mainframe specialty processor. One person pointed out that IBM says year-over-year growth of specialty engines has been 85%. Impressive? Yes, if you look at the percentage. I would like to see the raw numbers to determine whether the large growth is due to a small base last year. I have yet to been able to get IBM to give me these raw numbers.

I remember a couple years ago when Sun was boasting that year-over-year growth of their x86/x64 servers was 81%. But that’s because they hadn’t previously been selling a lot of x86/x64 servers. If you sell two the first year and four the next, that’s a 100% increase, but it doesn’t necessarily mean there was a huge amount of growth.