Virtual Storage Access MethodVirtual Storage Access Method (VSAM) is an IBM direct-access storage device (DASD) file storage access method, first used in the OS/VS1, OS/VS2 Release 1 (SVS) and Release 2 (MVS) operating systems, later used throughout the Multiple Virtual Storage (MVS) architecture and now in z/OS. Originally a record-oriented filesystem, VSAM comprises four data set organizations: key-sequenced (KSDS), relative record (RRDS), entry-sequenced (ESDS) and linear (LDS).
Access methodAn access method is a function of a mainframeoperating system that enables access to data on disk, tape or other external devices. Access methods were present in several mainframe operating systems since the late 1950s, under a variety of names; the name access method was introduced in 1963 in the IBM OS/360 operating system.
Direct-access storage deviceA direct-access storage device (DASD) (pronounced ) is a secondary storage device in which "each physical record has a discrete location and a unique address". The term was coined by IBM to describe devices that allowed random access to data, the main examples being drum memory and hard disk drives. Later, optical disc drives and flash memory units are also classified as DASD.Data set (IBM mainframe)In the context of IBM mainframe computers in the IBM System/360 line and its successors, a data set (IBM preferred) or dataset is a computer file having a record organization. Use of this term began with, e.g., DOS/360 and OS/360, and is still used by their successors, including the current VSE and z/OS. Documentation for these systems historically preferred this term rather than file.Record-oriented file systemIn computer science, a record-oriented file system is a file system where data are stored as collections of records. This is in contrast to a stream file system, where the data are treated as an unformatted stream of bytes. Record-oriented file systems are abstractions of files kept on paper in earlier times. A record might contain data associated with a particular, e.g., building, contact, employee, part, venue.
MVSMultiple Virtual Storage (MVS) is the most commonly used operating system on the System/370, System/390 and IBM ZIBM mainframe computers. IBM developed MVS, along with OS/VS1 and SVS, as a successor to OS/360. It is unrelated to IBM's other mainframe operating system lines, e.g., VSE, VM, TPF.OS/VS1Operating System/Virtual Storage 1, or OS/VS1, is a discontinued IBM mainframe computer operating system designed to be run on IBMSystem/370 hardware. It was the successor to the Multiprogramming with a Fixed number of Tasks (MFT) option of System/360's operating system OS/360. OS/VS1, in comparison to its predecessor, supported virtual memory (then called virtual storage). OS/VS1 was generally available during the 1970s and 1980s, and it is no longer supported by IBM.OS/VS2 (SVS)Single Virtual Storage (SVS) refers to Release 1 of Operating System/Virtual Storage 2 (OS/VS2); it is the successor system to the MVT option of Operating System/360. OS/VS2 (SVS) was a stopgap measure pending the availability of MVS, although IBM provided support and enhancements to SVS long after shipping MVS. SVS provides a single 16MiB address space which is shared by all tasks in the system, regardless of the size of physical memory.
Z/OSz/OS is a 64-bitoperating system for IBMz/Architecturemainframes, introduced by IBM in October 2000. It derives from and is the successor to OS/390, which in turn was preceded by a string of MVS versions. Like OS/390, z/OS combines a number of formerly separate, related products, some of which are still optional.
IBMAmerican multinational technology companyInternational Business Machines Corporation, doing business asIBM (nicknamed Big Blue), is an American multinationaltechnology company headquartered in Armonk, New York, and present in over 175 countries. It is a publicly traded company and one of the 30 companies in the Dow Jones Industrial Average.
Access methodAn access method is a function of a mainframeoperating system that enables access to data on disk, tape or other external devices. Access methods were present in several mainframe operating systems since the late 1950s, under a variety of names; the name access method was introduced in 1963 in the IBM OS/360 operating system.Direct-access storage deviceA direct-access storage device (DASD) (pronounced ) is a secondary storage device in which "each physical record has a discrete location and a unique address". The term was coined by IBM to describe devices that allowed random access to data, the main examples being drum memory and hard disk drives. Later, optical disc drives and flash memory units are also classified as DASD.Data set (IBM mainframe)In the context of IBM mainframe computers in the IBM System/360 line and its successors, a data set (IBM preferred) or dataset is a computer file having a record organization. Use of this term began with, e.g., DOS/360 and OS/360, and is still used by their successors, including the current VSE and z/OS. Documentation for these systems historically preferred this term rather than file.Record-oriented file systemIn computer science, a record-oriented file system is a file system where data are stored as collections of records. This is in contrast to a stream file system, where the data are treated as an unformatted stream of bytes. Record-oriented file systems are abstractions of files kept on paper in earlier times. A record might contain data associated with a particular, e.g., building, contact, employee, part, venue.MVSMultiple Virtual Storage (MVS) is the most commonly used operating system on the System/370, System/390 and IBM ZIBM mainframe computers. IBM developed MVS, along with OS/VS1 and SVS, as a successor to OS/360. It is unrelated to IBM's other mainframe operating system lines, e.g., VSE, VM, TPF.OS/VS1Operating System/Virtual Storage 1, or OS/VS1, is a discontinued IBM mainframe computer operating system designed to be run on IBMSystem/370 hardware. It was the successor to the Multiprogramming with a Fixed number of Tasks (MFT) option of System/360's operating system OS/360. OS/VS1, in comparison to its predecessor, supported virtual memory (then called virtual storage). OS/VS1 was generally available during the 1970s and 1980s, and it is no longer supported by IBM.OS/VS2 (SVS)Single Virtual Storage (SVS) refers to Release 1 of Operating System/Virtual Storage 2 (OS/VS2); it is the successor system to the MVT option of Operating System/360. OS/VS2 (SVS) was a stopgap measure pending the availability of MVS, although IBM provided support and enhancements to SVS long after shipping MVS. SVS provides a single 16MiB address space which is shared by all tasks in the system, regardless of the size of physical memory.Z/OSz/OS is a 64-bitoperating system for IBMz/Architecturemainframes, introduced by IBM in October 2000. It derives from and is the successor to OS/390, which in turn was preceded by a string of MVS versions. Like OS/390, z/OS combines a number of formerly separate, related products, some of which are still optional.IBMAmerican multinational technology companyInternational Business Machines Corporation, doing business asIBM (nicknamed Big Blue), is an American multinationaltechnology company headquartered in Armonk, New York, and present in over 175 countries. It is a publicly traded company and one of the 30 companies in the Dow Jones Industrial Average.*As an Amazon Associate I earn from qualifying purchases.