z/OS V1R6.0 DFSMS Access Method Services for Catalogs

cache), primary storage (DASD containinguncompressed data), migration level 1 (DASDcontaining data in a space-saving format), andmigration level 2 (tape cartridges containing data in aspace-saving format). See also primary storage, migrationlevel 1, migration level 2, object storage hierarchy.storage location. A location physically separate fromthe removable media library where volumes are storedfor disaster recovery, backup, and vital recordsmanagement.storage management. The activities of data setallocation, placement, monitoring, migration, backup,recall, recovery, and deletion. These can be done eithermanually or by using automated processes. The StorageManagement Subsystem automates these processes foryou, while optimizing storage resources. See alsoStorage Management Subsystem.Storage Management Subsystem (SMS). A DFSMSfacility used to automate and centralize themanagement of storage. Using SMS, a storageadministrator describes data allocation characteristics,performance and availability goals, backup andretention requirements, and storage requirements to thesystem through data class, storage class, managementclass, storage group, and ACS routine definitions.storage subsystem. A storage control and its attachedstorage devices. See also tape subsystem.stored record. A data record, together with its controlinformation, as stored in auxiliary storage.stripe. In DFSMS, the portion of a striped data set,such as an extended format data set, that resides onone volume. The records in that portion are not alwayslogically consecutive. The system distributes recordsamong the stripes such that the volumes can be readfrom or written to simultaneously to gain betterperformance. Whether it is striped is not apparent tothe application program.striped data set. In DFSMS, an extended-format dataset consisting of two or more stripes. SMS determinesthe number of stripes to use based on the value of theSUSTAINED DATA RATE in the storage class. Stripeddata sets can take advantage of the sequential datastriping access technique. Seestripe, striping.striping. A software implementation of a disk arraythat distributes a data set across multiple volumes toimprove performance.subrecord. The user definition level of a sphere, suchas an alternate index, cluster, or generation data set.sync point . An end point during processing of atransaction. A sync point occurs when an update ormodification to one or more of the transaction’sprotected resources is logically complete. A sync pointcan be either a commit or a backout.system data. The data sets required by z/OS or itssubsystems for initialization and control.system group. All systems that are part of the sameParallel Sysplex and are running the StorageManagement Subsystem with the same configuration,minus any systems in the Parallel Sysplex that areexplicitly defined in the SMS configuration.system-managed data set.assigned a storage class.A data set that has beensystem-managed storage. Storage managed by theStorage Management Subsystem. SMS attempts todeliver required services for availability, performance,and space to applications. See also system-managedstorage environment.system-managed tape library. A collection of tapevolumes and tape devices, defined in the tapeconfiguration database. A system-managed tape librarycan be automated or manual. See also tape library.system-managed volume. A DASD, optical, or tapevolume that belongs to a storage group. Contrast withDFSMShsm-managed volume, DFSMSrmm-managedvolume.Ttape configuration database. One or more volumecatalogs used to maintain records of system-managedtape libraries and tape volumes.tape library. A set of equipment and facilities thatsupport an installation’s tape environment. This caninclude tape storage racks, a set of tape drives, and aset of related tape volumes mounted on those drives.See also system-managed tape library, automated tapelibrary data server.Tape Library Dataserver. A hardware device thatmaintains the tape inventory that is associated with aset of tape drives. An automated tape librarydataserver also manages the mounting, removal, andstorage of tapes.tape storage group. A type of storage group thatcontains system-managed private tape volumes. Thetape storage group definition specifies thesystem-managed tape libraries that can contain tapevolumes. See also storage group.tape subsystem. A magnetic tape subsystemconsisting of a controller and devices, which allows forthe storage of user data on tape cartridges. Examples oftape subsystems include the IBM 3490 and 3490EMagnetic Tape Subsystems.tape volume. A tape volume is the recording space ona single tape cartridge or reel. See also volume.TCDB.See tape configuration data baseGlossary 523