Glossary

Glossary

archival

Provision for the storage of data at a lower cost, where it is not directly accessible to using programs. It includes the facility for restoring the data to the original medium on a demand basis.

archvol(s)

The tape volume(s) or disk data set(s) that contain the data sets that have been archived. Also the index to them that is kept in the files data set.

auto-restore

A CA Disk process by which data sets that have been archived are restored automatically if they are required by an application later. The data set can be restored by an online job or a batch job. This allows the DASD manager to keep free space available, yet gives the user access to data sets that are referenced infrequently. Data sets that have been archived to disk rather than to tape can be auto-restored with no operator intervention.

backup

A process by which a copy of a DASD data set is made, usually on tape, for the purpose of allowing the data set to be restored in the event of loss or damage to the original data set. Backup differs from the archive process, in that the data sets are copied, but not scratched or uncataloged.

• CA Disk backup processing provides for incremental backup, which limits copying to those data sets that have been changed since the last backup was taken. As each changed data set is identified, the backup copy is created and indexed, and then the change bit is turned off. To protect the data sets that are not changed, they are backed up regularly, such as once a week.

compress

The term compress has three different meanings in CA Disk.

• In PDS Compress, the term compress, describes the process of eliminating dead space in a PDS, or shrinking the size of the data set or its directory, by writing the PDS to a workfile, calculating reallocation requirements, then copying it back.
• The second usage applies to archive or backup processing. When data sets are copied to an archive medium, only active and used data blocks are read, thus resulting in PDS, ISAM and VSAM data sets being copied to the archive medium in compressed format. Subsequent restore or volume recovery results in the consolidation of several extents into one, a process sometimes referred to as defragmentation, and also the compression/reorganization of the data set.
• The third usage also applies to archive or backup processing, and is sometimes referred to as compaction. When data is being copied to an archive media, the data is analyzed and encoded (encrypted) into a new format that occupies less space. When the data set is restored, the data is automatically expanded (or de-compressed) into its original format.

data set index — DSNINDEX

A file containing a record for each data set that has been archived and has not yet expired. Separate records are created for each version of a data set that has been archived more than once. The existence of the data set index makes it possible to restore an archived data set by referencing only its name.

deferred processing

A means by which requests for certain actions are recorded and saved for later processing (queued processing). This is usually done to allow common requests to be grouped and processed in bulk in a more efficient manner, or to provide greater integrity by ensuring that certain actions are complete before other actions are begun.

dispose processing

The actual execution of those requests that at some prior time were deferred (queued); that is, deferred actions are disposed of later.

DSCB — data set control block

A record maintained by the operating system in a special DASD data set for each data set stored on a DASD volume. It contains attributes such as record format, block size and record length, as well as information about space occupied.

DSCL — data storage command language

A set of CA Disk commands providing a comprehensive, efficient common means to process VSAM and non-VSAM data sets. CA Disk to group all overlapping requests to allow all actions to be performed during a single pass of VTOCs or catalogs, preprocesses these commands.

explicit processing

Any CA Disk processing in which the data set(s) to be processed are not found by scanning either VTOCs or catalogs, but by processing a list of explicit names that either the user has provided, or have been extracted from the catalog. See "Implicit Processing".

file (first use)

A data set that has been archived and now exists as one of numerous internal files to the larger archive data set. This file represents a single archived data set and must be restored by a CA Disk utility function before an application program can reference it.

FILES (second use)

A set of logically related records maintained by CA Disk as a subfile or table. It is named after the DD statement FILES that points to it.

Files Data Set, FILES DS, or FDS

The direct access data set that has traditionally contained the FILES data. The entire BDAM data set is referred to as the files data set, while each subfile is usually referenced by its specific file name, such as the data set index file. Each file (subfile) is defined by an entry in the FILEDEFN member of parmlib.

Files Database, Files DB, or FDB

The Datacom database that contains the FILES data as tables using the original subfile names to reference them.

full pack backup

CA Disk uses the Volume-level backup method and is invoked by the VBACKUP command, making use of DSCL. Using the VRECOVER command restores data. For more information, see the chapter "VBACKUP/VRECOVER."

implicit processing

Any CA Disk processing in which the data set(s) selected for (or excluded from) processing are determined by scanning the input source, such as VTOCs or catalogs, from beginning to end, and applying user-specified criteria to determine what is or is not to be processed. The criteria can include factors such as last-use date, expiration date, create date, catalog status, blocksize, or being listed in a table. CA Disk permits multiple selection or exclusion criteria to be specified.

merge

The redistribution of archived data sets residing within several archive data sets (on tape or disk) to a smaller number of new archive data sets. Expired data sets are deleted, and the unexpired ones are sorted and grouped to use the archive media more efficiently.

migration

The movement of data from one type of storage medium to another without restricting accessibility. Reasons for migration include obtaining a lower-cost storage medium and changing the grouping of data.

MLA

Multi-Level Alias

PARMLIB — Parameter Library

A standard partitioned data set, or concatenation of data sets, containing both system-supplied members and user-supplied members that control various aspects of CA Disk processing.

prefix or group

A set of data sets or members that is identified with a common name prefix. A group name is indicated by placement of a slash (/) immediately following the last common character in a data set or member name. All data sets or members that have names that match on the number of characters preceded by the slash (/) are considered part of that group.

restore

The process by which an individual data set is restored (that is, copied from a backup or archive copy) to a DASD device. CA Disk permits restore processing without preallocation for ISAM, VSAM, PS, PO and DA data sets as well as for OS CVOL catalogs. Individual members of a PDS can also be restored. See also "Recover."

recover

The process by which a group of data sets, an entire volume, or a group of volumes is recovered (that is, copied from a backup or archive copy) to DASD. CA Disk recover processing provides for the same capabilities as restore processing, plus permits additional controls to be specified for the greater flexibility necessary for volume recovery.

retention control

An automated means by which CA Disk determines which data sets should be retained on disk and which removed.

SYSPARM — System Parameter

A means by which CA Disk can be tailored and implemented to meet the unique processing needs of each installation. Sysparms control various aspects of each CA Disk function. The default values are in effect unless they are overridden either temporarily (through overriding DD statements) or permanently (through specification in the SYSPARM member of the parmlib data set).

systems managed storage

The ability of an installation to specify the storage management rules and methodologies needed for their unique installation, and to then automate these within the system itself. Systems Managed Storage not only removes most if not all of the clerical effort and intervention that has historically been required, but must also provide the installation with control and flexibility in specifying its own rules and methodologies. If this second quality is overlooked, Systems Mismanaged Storage can easily be the result. The ability to manage and understand the automated system is of equal if not greater importance.

volume — level processing

CA Disk normally processes at the data set level. CA Disk can perform backup and recover processing at the volume level. For more information, see the chapter "VBACKUP/VRECOVER."

volume-level backup

This function (VBACKUP) is invoked through DSCL. It will produce a backup tape or tapes containing an entire DASD volume, starting at cylinder 0, track 0 and continuing through all used cylinders.

volume-level recover

This function is invoked under the RECOVER procedure, but through the VRECOVER command. When specified at recovery time, it overlays the entire volume in extent track order (i.e., from cylinder 0 to the end of the used cylinders).

VTOC — Volume Table of Contents

The data set on each DASD volume that contains a record called a data set Control Block (DSCB) for each data set stored on that volume. It also carries records that are used to account for free space.