What is the Multiple Virtual Storage?

Multiple Virtual Storage, more commonly known as MVS, is a mainframe operating system (OS) developed by International Business Machines™ (IBM) in 1974. This was a direct upgrade to the Multiprogramming with a Variable number of Tasks (MVT) operating system that came on the market in 1967. Both MVT and MVS are still commonly-used terms for the current system, even though the official name has moved away from the abbreviations. The current version of the Multiple Virtual Storage system is totally backward-compatible with older versions of the OS as well as the UNIX™ operating system.

The history of Multiple Virtual Storage begins with the development of MVT. This OS was supposed to be the system of choice for large IBM™ mainframes. Subsequent delays and problems with the initial release kept people from fully adopting the system, and many people stuck with the current Multiprogramming with a Fixed number of Tasks (MFT) OS.

The release of Multiple Virtual Storage was supposed to be the kick start that would bring people over to the new system. It was released as an update to the current IBM™ operating systems, particularly MVT. The differences in the programming were so great that it was widely seen as a new system entirely. As a result, users almost immediately began calling it MVS, and IBM™ soon did as well.

The abbreviation MVS was included in the proper name of every release from 1978 with MVS/Special Edition (MVS/SE) to 1988 with MVS/Enterprise System Architecture (MVS/ESA). In 1995, IBM™ released OS/390. While this system didn’t include MVS in its name, it was the direct successor to the system. Since the OS/390 release, MVS has not been put back into the name of the system updates.

While most versions of Multiple Virtual Storage were simply basic improvements to the core system, MVS/Systems Program (MVS/SP) contained support for UNIX™ systems. Since its release in 1980, the availability of UNIX™ programs, coupled with the backward compatibility of the IBM™ operating system, has created a wealth of programming for the MVS system. This cemented the OS as one of the largest mainframe systems in use.

In addition to Multiple Virtual Storage, IBM™ has several other operating systems on the market. The Transaction Processing Facility (TPF) line works primarily with airlines and other bulk-processing organizations to keep records organized and secure. The Virtual Machine (VM) line emulates mainframe operations on non-mainframe computers, the most well-known version being the Hercules system. Lastly, IBM maintains several UNIX™ and UNIX™-like operating system extensions that allow popular the OSs made by other companies to work on their mainframes as the stand-alone OS.