OpenVMS V7.3-1 running the CDE-based DECwindows GUI
|Developer||Digital Equipment Corporation, Compaq, Hewlett-Packard, VMS Software Inc|
|Written in||BLISS, VAX Macro, C, Ada, PL/I, Fortran, UIL, Pascal, SDL, C++, DCL, Message, Document|
|OS family||DEC OS family|
|Source model||Closed source, source available|
|Initial release||October 25, 1977|
|Latest release||OpenVMS 8.4-2L2 / July 10, 2017|
|Marketing target||High-end computer server|
|Update method||Concurrent upgrades,|
|Package manager||PCSI and VMSINSTAL|
|Platforms||VAX, Alpha, Itanium|
|Kernel type||Monolithic kernel with loadable modules|
|Default user interface||DCL CLI and DECwindows GUI|
OpenVMS is a multi-user, multiprocessing virtual memory-based operating system (OS) designed for use in time-sharing, batch processing, and transaction processing. It was first released by Digital Equipment Corporation in 1977 as VAX/VMS for its series of VAX minicomputers. OpenVMS also runs on DEC Alpha systems and the HP Itanium-based families of computers. OpenVMS is a proprietary operating system, but source code listings are available for purchase.
The name VMS is derived from virtual memory system, for one of its principal architectural features. When process priorities are suitably adjusted, it may approach real-time operating system characteristics. The system offers high availability through clustering and the ability to distribute the system over multiple physical machines. This allows the system to be tolerant against disasters that may disable individual data-processing facilities.
OpenVMS contains a graphical user interface (GUI), a feature that was not available in earlier original VAX/VMS releases. Prior to the introduction of DEC VAXstation systems in the 1980s, the operating system was used and managed from text-based terminals, such as the VT100, which provide serial data communications and screen-oriented display features. Versions of VMS running on DEC Alpha workstations in the 1990s supported OpenGL and Accelerated Graphics Port (AGP) graphics adapters.
Enterprise-class environments typically select and use OpenVMS for various purposes including mail servers, network services, manufacturing or transportation control and monitoring, critical applications and databases, and particularly environments where system uptime and data access is critical. System up-times of more than 10 years have been reported, and features such as rolling upgrades and clustering allow clustered applications and data to remain continuously accessible while operating system software and hardware maintenance and upgrades are performed, or when a whole data center is destroyed. Customers using OpenVMS include banks and financial services, hospitals and healthcare, network information services, and large-scale industrial manufacturers of various products.
In April 1975, Digital Equipment Corporation embarked on a hardware project, code named Star, to design a 32-bit virtual address extension to its PDP-11 computer line. A companion software project, code named Starlet, was started in June 1975 to develop a totally new operating system, based on RSX-11M, for the Star family of processors. These two projects were tightly integrated from the beginning. Gordon Bell was the VP lead on the VAX hardware and its architecture. Roger Gourd was the project lead for the Starlet program, with software engineers Dave Cutler (who would later lead development of Microsoft's Windows NT), Dick Hustvedt, and Peter Lipman acting as the technical project leaders, each having responsibility for a different area of the operating system. The Star and Starlet projects culminated in the VAX 11/780 computer and the VAX-11/VMS operating system. The Starlet name survived in VMS as a name of several of the main system libraries, including STARLET.OLB and STARLET.MLB.
Over the years the name of the product has changed. In 1980 it was renamed, with version 2.0 release, to VAX/VMS (at the same time as the VAX-11 computer was renamed to simply VAX). With the introduction of the MicroVAX range such as the MicroVAX I, MicroVAX II and MicroVAX 2000 in the mid-to-late 1980s, DIGITAL released MicroVMS versions specifically targeted for these platforms which had much more limited memory and disk capacity; e.g. the smallest MicroVAX 2000 had a 40MB RD32 hard disk and a maximum of 6MB of RAM, and its CPU had to emulate some of the VAX floating point instructions in software. MicroVMS kits were released for VAX/VMS 4.4 to 4.7 on TK50 tapes and RX50 floppy disks, but discontinued with VAX/VMS 5.0.
In 1991, VMS was renamed to OpenVMS as an indication for its support of "open systems" industry standards such as POSIX and Unix compatibility, and to drop the hardware connection as the port to DIGITAL's 64-bit Alpha RISC processor was in process. The OpenVMS name first appeared after the version 5.4-2 release.
The VMS port to Alpha resulted in the creation of a second and separate source code libraries (based on a source code management tool known as VDE) for the VAX 32-bit source code library and a second and new source code library for the Alpha (and the subsequent Itanium port) 64-bit architectures. 1992 saw the release of the first version of OpenVMS for Alpha AXP systems, designated OpenVMS AXP V1.0. The decision to use the 1.x version numbering stream for the pre-production quality releases of OpenVMS AXP caused confusion for some customers and was not repeated in the next platform port to the Itanium.
In 1994, with the release of OpenVMS version 6.1, feature (and version number) parity between the VAX and Alpha variants was achieved. This was the so-called Functional Equivalence release, in the marketing materials of the time. Some features were missing however, e.g. based shareable images, which were implemented in later versions. Subsequent version numberings for the VAX and Alpha variants of the product have remained consistent through V7.3, though Alpha subsequently diverged with the availability of the V8.2 and V8.3 releases.
In 2001, just prior to its acquisition by Hewlett-Packard, Compaq announced the port of OpenVMS to the Intel Itanium architecture. This port was accomplished using source code maintained in common within the OpenVMS Alpha source code library, with conditional and additional modules where changes specific to Itanium were required. The OpenVMS Alpha pool was chosen as the basis of the port as it was significantly more portable than the original OpenVMS VAX source code, and because the Alpha source code pool was already fully 64-bit capable (unlike the VAX source code pool). With the Alpha port, many of the VAX hardware-specific dependencies had been previously moved into the Alpha SRM firmware for OpenVMS. Features necessary for OpenVMS were then moved from SRM into OpenVMS I64 as part of the Itanium port.
Unlike the port from VAX to Alpha, in which a snapshot of the VAX code base circa V5.4-2 was used as the basis for the Alpha release and the 64-bit source code pool then diverged, the OpenVMS Alpha and I64 (Itanium) versions of OpenVMS are built and maintained using a common source code library and common tools. The core software source code control system used for OpenVMS is the VMS Development Environment (VDE).
Two pre-production releases, OpenVMS I64 V8.0 and V8.1, were available on June 30, 2003 and on December 18, 2003. These releases were intended for HP organizations and third-party vendors involved with porting software packages to OpenVMS I64.
The following are recent OpenVMS I64 releases:
|Version||Release date||End-of-life date||Notes|
|Old version, no longer maintained: V1.0||25 October 1977||?||VAX-11/780, Initial commercial release|
|Old version, no longer maintained: V2.0||April 1980||?||VAX-11/750|
|Old version, no longer maintained: V3.0||April 1982||?||VAX-11/730|
|Old version, no longer maintained: V4.0||September 1984||?||VAX 8600 and MicroVMS (for MicroVAX)|
|Old version, no longer maintained: V5.0||April 1988||?||VAX 6000|
|Old version, no longer maintained: V1.0 AXP||November 1992||?||first OpenVMS AXP (Alpha) specific version|
|Old version, no longer maintained: V6.0||June 1993||31 December 2012||VAX 7000 and 10000|
|Old version, no longer maintained: V6.1||April 1994||?||merging of VAX and Alpha AXP version numbers|
|Old version, no longer maintained: V7.0||January 1996||?||full 64-bit virtual addressing on Alpha|
|Old version, no longer maintained: V7.3||June 2001||31 December 2012||Last release for the VAX architecture.|
|Old version, no longer maintained: V8.0||June 2003||?||limited availability eval for Integrity|
|Old version, no longer maintained: V8.2||February 2005||30 April 2014||Common Alpha and Itanium release|
|Old version, no longer maintained: V8.3||September 2006||31 December 2015||Alpha, Itanium dual-core support|
|Older version, yet still maintained: V8.4||June 2010||31 December 2020||Virtual machine guest under HPVM. Clusters over TCP/IP. Last release from HP.|
|Older version, yet still maintained: V8.4-1H1||May 2015||31 December 2022||Support for "Poulson" Itanium processors, first release from VSI|
|Current stable version: V8.4-2||March 2016||31 December 2024||Support for systems with up to 64 cores and 1.5TB of RAM|
|Future release: V9.0||Q4 2019||N/A||x86-64 Early Adopter Release|
|Future release: V9.1||Q4 2020||N/A||x86-64 General Early Adopter Release|
|Future release: V9.2||2021||TBA||Itanium and x86-64 General Release|
|2021||TBA||Alpha General Release|
As of mid-2014, Hewlett-Packard (successor to DEC) licensed the development of OpenVMS exclusively to VMS Software Inc. (VSI). VMS Software will be responsible for developing OpenVMS, supporting existing hardware and providing roadmap to clients. The company has a team of veteran developers that originally developed the software during DEC's ownership.
OpenVMS offers many features that are now considered standard requirements for any high-end server operating system. These include:
The original graphical user interface for VMS was a proprietary window system known as VWS/UIS. This was later replaced by the DECwindows Motif user interface (based on CDE) layered on top of VMS's X11 compliant windowing system. DECwindows was also provided for the Ultrix operating system.
OpenVMS supports clustering (first called VAXcluster and later VMScluster), where multiple systems share disk storage, processing, job queues and print queues, and are connected either by proprietary specialized hardware (Cluster Interconnect) or an industry-standard LAN (usually Ethernet). A LAN-based cluster is often called a LAVc, for Local Area Network VMScluster, and allows, among other things, bootstrapping a possibly diskless satellite node over the network using the system disk of a bootnode.
VAXcluster support was first added in VMS version 4, which was released in 1984. This version only supported clustering over CI. Later releases of version 4 supported clustering over LAN (LAVC), and support for LAVC was improved in VMS version 5, released in 1988.
OpenVMS supports up to 96 nodes in a single cluster, and allows mixed-architecture clusters, where VAX and Alpha systems, or Alpha and Itanium systems can co-exist in a single cluster (Various organizations have demonstrated triple-architecture clusters and cluster configurations with up to 150 nodes, but these configurations are not supported by HP).
Unlike many other clustering solutions, VMScluster offers transparent and fully distributed read-write with record-level locking, which means that the same disk and even the same file can be accessed by several cluster nodes at once; the locking occurs only at the level of a single record of a file, which would usually be one line of text or a single record in a database. This allows the construction of high-availability multiply redundant database servers.
Cluster connections can span upwards of 500 miles (800 km), allowing member nodes to be located in different buildings on an office campus, or in different cities.
Host-based volume shadowing allows volumes (of the same or of different sizes) to be shadowed (mirrored) across multiple controllers and multiple hosts, allowing the construction of disaster-tolerant environments.
Full access into the distributed lock manager (DLM) is available to application programmers, and this allows applications to coordinate arbitrary resources and activities across all cluster nodes. This includes file-level coordination, but the resources and activities and operations that can be coordinated with the DLM are completely arbitrary.
OpenVMS V8.4 offers advances in clustering technology, including the use of industry-standard TCP/IP networking to bring efficiencies to cluster interconnect technology. Cluster over TCP/IP is supported in OpenVMS version 8.4, which was released in 2010.
With the supported capability of rolling upgrades and multiple system disks, cluster configurations can be maintained on-line and upgraded incrementally. This allows cluster configurations to continue to provide application and data access while a subset of the member nodes are upgraded to newer software versions.
OpenVMS has a very feature-rich file system, with support for stream and record-oriented IO, access control lists (ACLs), and file versioning. The typical user and application interface into the file system is via the Record Management Services or RMS.
OpenVMS represents system time as the 64-bit number of 100 nanosecond intervals (that is, ten million units per second; also known as a 'clunk') since the epoch. The epoch of OpenVMS is midnight preceding November 17, 1858, which is the start of Modified Julian Day numbering. The clock is not necessarily updated every 100 ns; for example, systems with a 100 Hz interval timer simply add 100000 to the value every hundredth of a second. The operating system includes a mechanism to adjust for hardware timekeeping drift; when calibrated against a known time standard, it easily achieves an accuracy better than 0.01%. All OpenVMS hardware platforms derive timekeeping from an internal clock not associated with the AC supply power frequency.
While the system is shut down, time is kept by a Time-of-Year ("TOY") hardware clock. This clock keeps time to a lower resolution (perhaps 1 second) and generally, a lower accuracy (often 0.025% versus 0.01%). When the system is restarted, the VMS 64-bit time value is recomputed based on the time kept by the TOY clock and the last recorded year (stored on the system disk).
The 100 nanosecond granularity implemented within OpenVMS and the 63-bit absolute time representation (the sign bit indicates absolute time when clear and relative time when set) should allow OpenVMS trouble-free time computations up to 31-JUL-31086 02:48:05.47. At this instant, all clocks and time-keeping operations in OpenVMS will suddenly fail, since the counter will overflow and start from zero again.
Though the native OpenVMS time format can range far into the future, applications based on the C runtime library will likely encounter timekeeping problems beyond January 19, 2038 due to the Year 2038 problem. Many components and applications may also encounter field-length-related date problems at year 10000 (see the Year 10,000 problem).
Among OpenVMS's notable features is the Common Language Environment, a strictly defined standard that specifies calling conventions for functions and routines, including use of stacks, registers, etc., independent of programming language. Because of this, it is possible and straightforward to call a routine written in one language (Fortran) from another (COBOL), without needing to know the implementation details of the target language. OpenVMS itself is implemented in a variety of different languages (primarily BLISS, VAX Macro and C), and the common language environment and calling standard supports freely mixing these languages, and Ada, PL/I, Fortran, BASIC, and others. This is in contrast to a system such as Unix, which is implemented nearly entirely in the C language.
The common language programming environment is described in the OpenVMS Calling Standard and the OpenVMS Programming Concepts manuals. This provides mixed-language calls, and a set of language-specific, run-time library (RTL), and system service routines. The language calls and the RTLs are implemented in user-mode shareable images, while the system services calls are generally part of the operating system, or part of privileged-mode code. This distinction between languages and RTLs and system services was once fairly clean and clear, but the implementations and specifics have become rather more murky over the years.
Macro32 (an assembler on OpenVMS VAX, and a compiler on OpenVMS Alpha and on OpenVMS I64) is available within and integrated into OpenVMS. BLISS compilers are available for download, as are various ports of Perl, PHP, Ruby and other languages. Java SE is provided with OpenVMS. C, Fortran and other languages are commercial products, and are available for purchase.
Various utilities and tools are integrated, as are various add-on languages and tools.
Many programming examples are available via the OpenVMS FAQ.
The VMS Debugger supports all DEC compilers and many third party languages. It allows breakpoints, watchpoints and interactive runtime program debugging either using a command line or graphical user interface.
In a manner similar to Unix, VMS defines several standard input and output streams with these logical names:
SYS$INPUT - Standard input. Used interactively, this represents the terminal keyboard. Used in a batch file, it is batch file lines not preceded with a $ symbol, or specified as an input deck using the DECK command.
SYS$OUTPUT - Standard output. Used interactively, this is the terminal display. Used in a batch file, it outputs to the screen (if run interactively) or to the log file when run noninteractively.
SYS$ERROR - Standard error. Used interactively, this is the terminal display. In a batch file, it is the screen display (if run interactively), or to the log file if run interactively, or in the special case of RUN /DETACH, to the output file or device specified with the /ERROR= parameter.
SYS$COMMAND - Does not have a direct analogue in the Unix model. Used interactively, it will read from the terminal. Used in a batch file when run interactively, it will read from the terminal. Used in a batch file run noninteractively, it will read from the SYS$INPUT stream (if one is defined), otherwise it will read nothing and return end of file.
This section needs expansion. You can help by adding to it. (April 2011)
OpenVMS provides various security features and mechanisms, including security identifiers, resource identifiers, subsystem identifiers, ACLs, and detailed security auditing and alarms. Specific versions evaluated at DoD NCSC Class C2 and, with the SEVMS security enhanced services support, at NCSC Class B1, per the NCSC Rainbow Series. OpenVMS also holds an ITSEC E3 rating (see NCSC and Common Criteria)./ Passwords are hashed using the Purdy Polynomial.
A 33-year-old vulnerability in VAX/VMS and Alpha VMS was discovered in 2017. This allowed anyone with access to the DCL command line in a system with a default configuration to bypass all system security and take complete control of the system. The CVE number is CVE-2017-17482.
OpenVMS supports the following industry standard and open-source tools and applications:
DEC's OpenVMS Operating System documentation for various releases, and for various core OpenVMS layered products, is available online at the HPE website.
Software Product Descriptions (SPD) are introductory and legal descriptions of various products, listing the various supported capabilities and product features. SPD documents for many OpenVMS-related products, and for OpenVMS itself, are available at Hewlett Packard Enterprise
The OpenVMS Frequently Asked Questions (FAQ) contains information and pointers associated with OpenVMS, and is available in various formats at HoffmanLabs
The current OpenVMS release is 8.4-2L1 (Hudson), previous were OpenVMS V8.4-1H1 for Integrity servers, OpenVMS V8.4 for Alpha and OpenVMS V7.3 for VAX servers.
HP provides Current Version Support (CVS) and Prior Version Support (PVS) for various OpenVMS releases. The OpenVMS Roadmap guaranteed PVS status for specific releases (V5.5-2, V5.5-2H4, V6.2, V6.2-1H3, V7.3-2) until 2012, and only then ending with 24 months' prior notice. CVS is provided for the current release and for the immediately prior release.
On July 31, 2014, VMS Software, Inc. (VSI) announced that HP named VSI as the sole developer of future versions of the OpenVMS operating system and its layered product components. The first release, VSI OpenVMS Version 8.4-1H1 (Bolton), was released June 1, 2015. Next releases will support the latest Itanium hardware. The availability of VSI OpenVMS on x86-based servers for early adopters is planned for 2018. VSI has assembled a Massachusetts, US-based team of veteran OpenVMS developers, many harkening back to the core DEC team responsible for the initial and ongoing development of OpenVMS.
Some of the industry standards claimed in the OpenVMS Software Product Description are:
Despite being a proprietary commercial operating system, in 1997 OpenVMS and a number of layered products were made available free of charge for hobbyist, non-commercial use as part of the OpenVMS Hobbyist Program. Since then, several companies producing OpenVMS software have made their products available under the same terms, such as Process Software and MVP Systems.
In 2011, HP staff took over the administration of the hobbyist licences. Registration was simplified and remained zero cost. The process from registering to receiving Product Authorisation Keys typically takes about one working day. Software kits for operating system and layered products were made available on request via FTP download (previously it had to be shipped on CD which was chargeable). This process is not fully automatic and requires authorisation by HP Hobbyist Program staff.
FreeVMS is an attempt to develop an open source operating system following VMS conventions. As of April 2019 the associated mailing list had been totally inactive for two years and shown limited activity for some years prior to that. FreeVMS supported the x86-64 architecture using an L4 microkernel.
VMS is in some ways an ancestor of Windows NT, together with RSX-11 and an unreleased object-based operating system developed by Dave Cutler for DEC Prism. This lineage is made clear in Cutler's foreword to "Inside Windows NT" by Helen Custer.
OpenVMS-related vocabulary include:
VAX architecture features .... a virtual memory system (which is ... where the name OpenVMS came from)
the Alpha hardware platform, including Alphas running on x86-based emulators. This OpenVMS Alpha version is based on, and inherits the benefits of, the latest version of VSI OpenVMS Integrity V8.4-2L1, released in September 2016.