OpenVMS is an
operating system, which
Digital Equipment Corporation (DEC) originally developed for their
servers. Later, it was ported, and now also runs on
DEC Alpha and
Itanium-based systems. It is a 32 bit operating system. When it was published in 1977, it was one of the first of its kind. OpenVMS is capable of supporting many concurrent users; each user is able to run several programs at the same time. It was also one of the first operating systems with a
Graphical user interface, the
VAXstation was a very popular
workstation at the time. OpenVMS uses
virtual memory, and was originally developed as a
batch processing system. It was made for
transaction processing, and is a
real-time system. The jobs users submit can have a higher priority than those of the operating system. The operating system offers high
clustering: The system load can be distributed over multiple computers. That way, the system is "disaster-tolerant": One machine that fails will not shut the operation down.
OpenVMS introduced many features that became standard in later operating systems:
Today, OpenVMS is used in many enterprises where availability and uptime are critical: These include
insurance companies. System up-times of over a decade have been reported.
 A feature called "rolling upgrade" allows to upgrade software or hardware without the need to shut the system down. A data center that is destroyed will not lead to downtime either, if the system is configured properly. Customers using OpenVMS include banks and financial services, hospitals and healthcare, network information services, and large-scale industrial manufacturers of various products.