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While backwards compatibility was maintained, the older access methods suffered from performance problems due to the address translation required for virtual storage. The KSDS organization was designed to replace ISAM, the Indexed Sequential Access Method. Changes in disk technology had meant that searching for data in ISAM data sets had become ...
IDCAMS ("Access Method Services") generates and modifies Virtual Storage Access Method (VSAM) and Non-VSAM datasets. IDCAMS was introduced along with VSAM in OS/VS; the "Access Method" reference derives from the initial "VSAM replaces all other access methods" mindset of OS/VS. IDCAMS probably has the most functionality of all the utility ...
5740-AM3 Sequential Access Method Extended (SAM-E) SAM-E improves the performance of BPAM, BSAM and QSAM on direct access storage devices. 5740-AM8 Access Method Services Cryptographic Option 5748-UT2 Offline 3800 Utility. In June 1980, IBM announced MVS/System Product (MVS/SP) as a replacement for MVS/SE.
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]
An access method is a function of a mainframe operating 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. [ 1 ]
OS/360, officially known as IBM System/360 Operating System, [1] [2] is a discontinued batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964; it was influenced by the earlier IBSYS/IBJOB and Input/Output Control System (IOCS) packages for the IBM 7090/7094 [citation needed] and even more so by the PR155 Operating System for the ...
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.
One common method to address these limits is to use multiple levels of virtualization. In several storage systems deployed today, it is common to utilize three layers of virtualization. [4] Some implementations do not use a mapping table, and instead calculate locations using an algorithm. These implementations utilize dynamic methods to ...