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Virtual Storage Access Method (VSAM) [1] 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.
A virtual storage area network (virtual SAN, VSAN or vSAN) is a logical representation of a physical storage area network (SAN). A VSAN abstracts the storage-related operations from the physical storage layer, and provides shared storage access to the applications and virtual machines by combining the servers' local storage over a network into a single or multiple storage pools.
In 1972 IBM announced the first release of the OS/VS2 operating system for the IBM System 370 systems; that release later was known as Single Virtual Storage . In 1974 IBM announced release 2.0; that release and all subsequent releases became known as Multiple Virtual Storage . All releases of OS/VS2 were available to no charge because the ...
MVS/XA, or Multiple Virtual Storage/Extended Architecture, was a version of MVS that supported the 370-XA architecture, which had a new I/O architecture and also expanded addresses from 24 bits to 31 bits, providing a 2 gigabyte addressable memory area. [9]
Virtual Disk - a unit of storage presented to the host. The release 6 GUI refers to a VDisk as a Volume. Managed Disk (MDisk) - a unit of storage (a LUN) from a real, external disk array, virtualized by the SVC. An MDisk is the base to create an image mode VDisk.
Furthermore, if a different device is connected to the port in question, it will gain access to any resources the previous host had access to. WWN zoning (also called name zoning) restricts access by a device's WWN. As the WWN is on the host, the port the host is connected to can be moved and access is still preserved.
Storage systems can provide either block accessed storage, or file accessed storage. Block access is typically delivered over Fibre Channel, iSCSI, SAS, FICON or other protocols. File access is often provided using NFS or SMB protocols. Within the context of a storage system, there are two primary types of virtualization that can occur:
Direct-attached storage (DAS) is digital storage directly attached to the computer accessing it, as opposed to storage accessed over a computer network (i.e. network-attached storage). DAS consists of one or more storage units such as hard drives , solid-state drives , optical disc drives within an external enclosure .