Most users may well find that the desire to upgrade to ESA is prompted more by the availability of the new version 3 of MVS/Data Facility Product, DFP, than it is by the need to start allowing their data a whole 16Tb of space in which to romp. The key feature of the new DFP […]
Most users may well find that the desire to upgrade to ESA is prompted more by the availability of the new version 3 of MVS/Data Facility Product, DFP, than it is by the need to start allowing their data a whole 16Tb of space in which to romp. The key feature of the new DFP is that it is designed to lift from the programmer a large part of the burden of determining where on disk data should be stored. IBM claims that MVS/DFP 3 provides new storage management functions to make system-managed, administrator-controlled storage a reality. The new version of MVS/DFP and other individual products of the Data Facility family, together with RACF, make up Data Facility Storage Management Subsystem, DFSMS (better get to know those damned acronyms). This subsystem is designed to simplify the management and use of external storage resources – disk – by providing a device-independent means of requesting services by data set. Among other things, this makes it easier to move on to new storage devices – and will be the base to exploit future storage subsystem function. MVS/DFP 3 with MVS/SP 3 uses the new Enterprise Systems Architecture/ 370 and is offered to enable IBM subsystems and user applications to take advantage of the data spaces and hiperspaces created by ESA/370. Centralised controls The storage management subsystem introduces a centralised set of controls defined by the storage administrator which will move the focus for storage management from the end user to the storage administrator while providing more services for the user and applications, IBM claims. It is designed to provide an easier way for the end user to define data and for the storage administrator to specify data set service requirements and to manage resources. It provides centralised assignment of services to new data sets. The service definitions are created and maintained by the storage administrator, saved in a data set, and used during allocation of new data sets. During allocation, specific service definitions are selected and assigned to individual data sets based on the parameters in the allocation process. The actual services are provided by DFSMS during the life cycle of the data set, and can be introduced progressively, taking place over a period of time determined by the customer. At no time is the customer required to make a system-wide switch to an unfamiliar application or data environment and co-existence of data and applications is provided between the current and the new environments. But data on system-managed storage volumes should not be shared between MVS/DFP 3 and DFP 2 systems. It includes four new ways in which to classify data set services: Data class defines the data characteristics; Management class defines how the data set activity should be managed; Storage class defines the hardware performance and availability requirements; and Storage group defines groups of physical devices. The classifications, together with automatic class selection, are there to enable the administrator to manage storage more effectively and reduce user involvement. As well as ease of use for end users, IBM reckons that the new facilities should enable more efficient use of the available disk space. The assignment of a storage class to a new data set puts that data set under system-managed storage. Storage class can be used to determine the level of disk service a data set will receive and whether the data set will get performance preference over other data sets. The storage class routine can be used to intercept data being allocated to a mass storage system or tape device and change the destination to a direct access device. Or a device-dependent allocation can be intercepted so the placement of the data set is device-independent. Through an MVS/DFP management class selection routine, data set services such as backup frequency and space management, can be performed at the data set level, rather than at the volume level. The storage group selection routine defines how the data relates to the physical devices, by assigning one or more storage groups to each
new system-managed data set. New applications are also provided in the Interactive Storage Management Facility, ISMF, for the definition, alteration, deletion and listing of data classes, storage classes, management classes, and storage groups. New applications are also provided in ISMF to edit, translate, validate, test and delete automatic class selection routines. Data set and volume applications are enhanced to support the new controls for interactive reporting purposes. All system-managed data sets are catalogued in Integrated Catalog Facility catalogues, which have been updated to contain new fields. Access Method Services commands have been updated to include new tasks involving the use of classes and specification of system-managed data sets. Suspicious-minded The attractions are obvious, but the very suspicious-minded will see snags: once you hand over storage allocation to IBM, and can no longer get a picture of exactly what is happening on your disks, the way is open for IBM, for marketing reasons, to tweak the software so that it makes more efficient use of one type of disk than it does of another. If IBM wants to migrate users quickly to a new generation of drives, it could use the storage management facilities to ensure that the benefit of the new disks was in excess of the difference between their capacities and those of the old ones, and plug-compatible manufacturers will fear that IBM will use it as a weapon against them. The planned availability for the new product is December 1988 in the US. To activate Storage Management Subsystem functions fully within MVS/DFP Version 3, an enabling DFP Program Temporary Fix will be provided under controlled introduction and Data Facility Storage Management Subsystem is designed specifically for use in an operating environment supported by the new Enterprise System Architecture/370. The company says that while MVS/SP-JES2.2 support will begin controlled introduction in third quarter 1989 to accommodate the Storage Management Subsystem functions of MVS/DFP 3 in the MVS/XA environment. This support, however, will not provide the function and performance enhancements available in the MVS/SP Version 3. The price for the new release is $54,000 a month on Group 20 and 30 machines, $86,400 ion Group 40 machines.