ISVs Push Back Against zPDT Sunsetting
The platform allows ISVs to test their products on-premises in an emulated z/OS environment, but only for another 13 months
Members of the mainframe ISV community are telling IBM if it ain’t broke, don’t replace it, after the sunsetting of the System z Personal Development Tool (zPDT) was announced in September.
By emulating a Z environment on x86 architecture, zPDT allows ISVs to test their products without the expense of owning and operating a mainframe. That option will no longer be supported at the end of 2026. Despite the existence of a cloud-based replacement, the ISV community has concerns that the change will force companies to purchase their own mainframe for testing—if they can afford it.
“A lot of vendors—this is going to cost them a lot of money and a lot of pain that they really don’t need,” says Vertali Technical Director Mark Wilson, who is spearheading the ISV response to IBM’s move.
One of Wilson’s concerns is the current state of the new IBM z/OS Hosted On‑Demand program for ISVs (HDISV), IBM’s replacement for zPDT. According to Wilson, HDISV doesn’t currently support zVM or sysplex. That’s an automatic disqualifier for Vertali, though Wilson is optimistic the service will include those components before the end of 2026.
In a letter sent to ISVs, IBM noted that sysplex support is on the roadmap for HDISV in 2026. IBM’s Remote Development Program, though not being billed as the direct replacement for zPDT, supports both sysplex and zVM.
In an email sent to ISVs, IBM stated, “Our goal is to minimize disruption and ensure the required capabilities are available while also delivering enhanced performance and security for test and development environments.” The email outlined efforts underway to enhance HDISV, including access to the Linux layer to allow multiple OSes to run (including VSEn) and zIIPS capability.
Concerns Over IP Security
Beyond the cost of a mainframe, a more intractable concern may be the security of ISV’s intellectual property (IP). With HDISV, “your IP would be on somebody else’s computer,” Wilson tells TechChannel. “People talk about the cloud, and I keep saying to people: There’s no such thing; it’s just somebody else’s computer.
“And this is what they’re asking us to do—put all of our intellectual property, all the stuff that we’ve written and worked on for years and years, on their system. No, this is why we like zPDT in our data center. It’s in our office, it’s ours, we control it.”
One alternative to purchasing a mainframe or using HDISV could be to rent LPARS for testing, but licensing restrictions prevent that, Wilson notes. If IBM would allow it, “somebody could put together a hardware solution and rent LPARs out to all the other vendors in a much more controlled and smaller environment,” he says.
Mainframe Sticker Shock
While there are hopes that IBM will heavily discount Z hardware bundles that are sold for testing purposes, an adequate mainframe system would likely cost larger ISVs roughly $1 million at retail, according to Roxane Rosberg, VP of customer relations at Vanguard Integrity Professionals. “People perceive the mainframe as being expensive already. All those costs just keep adding up, and it hurts the industry,” Rosberg says.
A letter sent to ISVs noted that IBM is exploring options to give them specialized terms for an on-premises offering based on LinuxONE and Test Accelerator for Z (TAZ).
Though running a mainframe on-premises comes with sizable and ongoing costs, Wilson says he knows enough about mainframe security to know he wants to keep his most prized data on-premises. “I’m a pen tester and a security person. I know what people can do with this technology. If you’ve got hardware control, it’s not for me,” he says.
Absent zPDT, his preference—which he believes a number of other ISVs share—is to purchase a mainframe and use it onsite, if they can make the finances work. “If we can’t, we may have no choice but to go HDISV and just change the way we do things and make sure we protect our IP really, really tightly,” Wilson says.
IBM declined an interview request from TechChannel regarding the zPDT sunsetting, but provided a statement saying HDISV is being offered as a “turnkey solution” to help ISVs “achieve faster time‑to‑market, strengthen security, and simplify operations.” With HDISV, IBM is promising “improved performance, a streamlined user experience, and flexible monthly billing.”
ISVs Curious About Rationale
Both Wilson and Rosberg are dissatisfied with IBM’s explanations for the zPDT retirement. “What’s really disappointing,” Wilson says, “is that the zPDT solution really, really works. It’s a great solution for ISVs. It really is.”
Given the important role ISVs play in the mainframe ecosystem, Rosberg foresees ripple effects if ISVs are harmed. She notes that ISVs are financial linchpins and drivers of technology. “If we’re putting a product together, nine times out of 10 it’s because it’s something IBM themselves don’t do,” she says.
Wilson believes IBM won’t reverse its decision, no matter how much noise the ISV community makes, but he doesn’t envision a “doom and gloom” scenario.
“My biggest issue,” he says, “is I still don’t understand why.”