In February 1988, IBM announced ESA/370, which provided new capabilities for the IBM ES/3090 processors, including access registers, linkage stacks and PR/SM. The volume of data to be processed had risen dramatically over the preceding decade. Access registers made it easy to separate application code from data, resulting in improvements in data volume handling capabilities and data isolation. ESA/370 provided a new virtual storage space for data only, called a data space. Unlike a cross-memory address space, no application code can execute in a data space.
Linkage stacks simplify cross-memory applications, and provide easy-to-use program calls/program returns between address spaces, as well as program calls/program returns within a single address space. Linkage stack also offer associated recovery routines that reduce the need for ESTAEs. Today's DB2 uses linkage stack facilities.
Once again, MVS/SP V2 and MVS/XA DFP V2 were reworked into the next level of the MVS operating system, MVS/ESA. MVS/ESA product levels were MVS/SP Version 3 and MVS/DFP Version 3. MVS/DFP V3 also contained a significant productivity enhancement called system-managed storage. System-managed storage allows the operating system to place and control data on external devices, based on data characteristics and usage. System managed storage significantly improves DASD utilization, and reduces the work that people, particularly the storage administrator, must do. MVS/DFP 3.2 provided PDSEs, a new 4K physical blocksize structure for partitioned datasets. PDSEs eliminate periodic compresses and the need for careful space pre-planning. MVS/DFP V3 offered a network file server, supporting Sun Microsystem's remote procedure call (RPC) through TCP/IP. The network file server represented a first functional step toward making MVS/ESA operate in an open-system environment. MVS/ DFP V3 also introduced a new access method, OAM, in support of optical disk technology.
Data spaces addressed a long-standing customer requirement - the ability to access and process data more quickly. Data spaces allow large amounts of data to reside in processor storage, essentially trading storage for I/O access time. Data in a data space is byte-addressable, and can be manipulated directly by a program in an address space. Two new services, LLA and VLF, allow the operating system and subsystems to easily utilize data spaces for program libraries, CLISTs and data objects.
MVS/SP V3 also provided a special high-speed form of data space called a Hiperspace. Hiperspace data always resides in expanded storage, and must be moved to the address space for manipulation. However, it does not use the paging mechanism. Movement in 4KB or multiples of 4KB blocks bypasses the high-speed buffer. Since data in the high-speed buffer is not disturbed, the buffer hit ratio is improved. VSAM LSR and DFSORT utilize Hiperspaces to improve performance. Another storage technique, Hiperbatch, allows interim VSAM or QSAM sequential data to be kept in a Hiperspace for improved batch processing.
Assembler and FORTRAN were subsequently updated to enable user applications to directly access data in data spaces. Callable services are provided so user applications can utilize Hiperspaces.
MVS/ESA SP 3.1.3 with RACF 1.8 received a B1 security rating from the U.S. Department of Defense. B1 provides the appropriate environment for applications that must have mandatory label security protection.
The first release of MVS/ESA was delivered in August 1988.
To provide for an orderly migration from MVS/XA to MVS/ESA, two provisions were made. MVS/XA DFP 2.4 was updated to run with MVS/SP V3 until such time as MVS/DFP V3 could be installed. No Hiperspace support was available with MVS/XA DFP 2.4. For users needing system-managed storage before migrating to MVS/ESA, MVS/DFP V3 was upgraded to run on MVS/XA with starter-level, system-managed storage function.
OS/VS2 MVS 3.8 remained an installation prerequisite for new users of MVS.
In September 1990, IBM announced ESA/390 and the ES/9000 family of processors. Prime new concepts were Sysplex and ESCON. Again, the base control program was enhanced to support the new architecture, resulting in MVS/ESA SP Version 4.
A new component, XCF, was added, which allowed authorized applications on one system to communicate via CTC with other specified authorized applications on another MVS/ESA SP Version 4 system. If an application or a system begins to fail, the companion application on the other system can be called into service.
XCF presented the opportunity for higher levels of availability. OPC/ESA, CICS/ESA XRF and JES2 V4 have been modified to utilize XCF services for takeover and recovery. XCF can also be used with PR/SM ARF to automatically reconfigure processor storage when takeover occurs.
Another new component, APPC/MVS, provided a new level of application portability and interoperability with the other SAA systems. APPC applications can now operate in client/server fashion and may be ported from one operating system to another when written to the CPI-C interface.
Dynamic I/O reconfiguration was realized through ESCON architecture, the ESCON Manager licensed product, and MVS/ESA SP V4 HCD. Specified channel attached devices can be attached and configurations changed without bringing the system down, reducing PORs and IPLs. Support was also provided in NCP to dynamically add preconfigured lines with HCD. A common and consistent front end was also developed for HCD and ESCON Manager, using the ScreenView feature. ScreenView is part of MVS/ESA SP 4.3. Once again, productivity for the system programmer was improved.
PR/SM EMIF, an extension announced for ESA/390 in June 1992, is also supported by MVS/ESA SP 4.3. PR/SM EMIF allows sharing of ESCON channels among logical hardware partitions, which should increase configuration flexibility and provide cost savings through reduction in the number of channels required for PR/SM.
DFSMS/MVS announced in May 1992, integrates and expands the storage and program management functions previously available in MVS/DFP V3, DFHSM and DFDSS. A new feature, Removable Media Manager, was also added. DFSMSrmm allows tapes, both automated and manual libraries, to have the full automated management support provided by DFSMS.
DFSMS/MVS has since added a concurrent copy function that provides potential for improved data availability during the data backup process. DFSMS/MVS is capable of improving application performance for sequential data sets through data striping. Data striping is a high performance data transfer technique that utilizes parallel data transfer.
Another new product, DFDSM, added to the MVS system-management capability. DFDSM allows the system to act as a file backup and archive server for LAN file servers and workstations. It also allows applications access to local or distributed record data of DDM systems. Remaining OS/VS2 MVS 3.8 components were repackaged into existing licensed products and the requirement to have MVS 3.8 as an installation base was removed with MVS/ESA SP 4.2.2.
In 1992, IBM further simplified the installation process through a group of new offerings called CustomPacs. One of these, the SystemPac, is a system replacement option that goes beyond CBIPO in building and customizing. Two others, ProductPac and ServicePac, are system upgrade options, tailored to a particular system rather than to an establishment. They are simpler to install and require less SMP/E knowledge than CBPDO.
Throughout the existence of MVS, heavy emphasis bas been placed on reliability. With MVS/ESA SP V4, we increased our efforts to ensure quality and reliability. Both existing code and newly developed code were examined for defects, and corrections included in the product. However, quality means more than code-defect removal. Installation procedures, IPL actions, publications and other forms of documentation were also reviewed and updated.
MVS/ESA SP 4.3 OpenEdition services provide an expanded role for MVS's participation in an open systems environment. POSIX and OSF/DCE are currently being developed to run on MVS/ESA SP 4.3. NetView and DFDSM are key products upon which MVS system management and network management will be built. MVS/ESA will continue to play a leadership role in our customers' enterprises within the open-system environment. It will act as the enterprise-wide data server and database manager; it will provide data protection and integrity; it will be the enterprise-wide network, manager, providing upload/download, backup and recovery services; it will be the base for high-volume, high-response transaction processing; an application server; a technical computing platform; a high volume cryptographic platform; a data compression platform, and a query server.
Needless to say, MVS remains a superior batch processing system. The addition of VIO to expanded storage, Hiperbatch, Batch LSR and data striping have contributed significantly to this capability.