IT Management

Anyone who has followed the Virtual Machine (VM) Operating System (OS) over the last 20 years knows that times have often been tough for VM and its users. The good news is that VM is undergoing a renaissance. The term “renaissance” is particularly apt in this case. Derived from words meaning “new birth,” renaissance is defined as, 1) a revival of intellectual or artistic achievement and vigor: the Celtic Renaissance, or 2) the period of such a revival. VM has indeed been reborn in a new role.


IBM’s VM OS has never followed a predictable path. Created to allow testing multiple copies of OS/360 on a single piece of expensive hardware, VM’s flexibility quickly made it the original personal computing environment. Each user was able to customize his or her virtual machine and run any programs available, without requiring data center assistance or authorization. VM spread to IBM installations across the business spectrum, and was also popular with universities because of its flexibility and efficiency

In the early 1980s, IBM announced an Object Code Only (OCO) policy for VM. Source code would not be available for future releases. Since VM installations traditionally made extensive use of the source for debugging and local system enhancements, this was disappointing. Customers lobbied IBM and slowed OCO progression, but were unsuccessful until other factors caused VM to drop “below the radar” for IBM executives. After that, source was gradually restored for many modules. Later, IBM announced that future modules would have source provided unless there was a specific asset-protection (trade secret) issue involved.

Even without the OCO battle, parts of IBM seemed to hate its own product at times during the 1980s and 1990s. Customers reported IBM representatives telling them “VM is going away,” and “VM will be unsupported soon.” VM’s support of new hardware often ran months or years behind MVS, which helped bolster its image as a dying product. This occurred even though IBM itself depended heavily on VM, using it for corporate e-mail and many critical systems, including:

  • Hands-On Network Environment (HONE), IBM’s internal database/ ordering/tracking system
  • IBMLink (the customer equivalent of HONE).

However, fear, uncertainty, and doubt (FUD) led many committed VM installations to forge plans to migrate off of VM. Fueling the FUD were the messages received by customer management, combined with the client/server movement’s ascent — and, later, distributed systems. Some sites have succeeded, although many companies are now six to eight years into two-year migration plans, with no end in sight!

Meanwhile, IBM’s downsizing hit the VM team hard. From a peak of more than 1,000 programmers, planners, and support staff, the VM organization has shrunk to fewer than 150. However, as one might hope, the current crew is topnotch, and has achieved amazing results in supporting existing code and adding new function and hardware support.

Another factor in VM’s decline during the 1990s was the shift that occurred as e-mail moved from the mainframe (PROFS/OfficeVision) to the LAN (Microsoft Exchange and Lotus Notes). End users no longer wanted VM accounts; they wanted PCs on their desktop. Attempts to add a VM Graphical User Interface (GUI) were less than successful, due both to performance issues and difficulty mapping 3270 displays to modern GUIs.

During these “decades of doubt,” the VM faithful persevered. Customers at local and national user groups, such as SHARE, continued to find innovative ways to use VM. In some cases, upper management “forgot” that they used VM, and were occasionally surprised to find that critical systems were humming quietly along on this “dead” OS.

The IBM VM team churned out new releases, often annually or even more frequently. As systems grew, and the builtin limit of 16 megabytes (MB) became an issue, the VM/SP High-Performance Option (VM/SP HPO) emerged. HPO was VM/SP with improved scheduling and the ability to use up to 64MB of real memory, although the storage above the 16MB line was used only for high-performance page space.

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