Glossary

A term in italic font means that it is explained somewhere else in the glossary.

additional mirror unit

Additional mirror disk which can be split without impairing ongoing input/output operation.

allocation unit

Smallest possible unit of storage space available to the system when creating a file.

control volume set

Labeled volume set of an SM pubset; it contains the administration information for the whole pubset.

data backup

Periodical creation of copies of the data set so that it can be restored in the event of data loss due to a hardware error or inadvertent deletion.

data compression

Used to reduce the number of volumes required for backup. FDDRL recognizes two types of data compression: hardware compression, which is performed by MTC devices, and software compression.

disk format

FDDRL supports disks with the formats KEY, NK2 and NK4. KEY disks can only be copied or restored to KEY disks, NK2 disks only to NK2 disks, and NK4 disks only to NK4 disk

disk set

Save entity of FDDRL: When saving, FDDRL combines multiple disks to form a disk set and saves this to a tape set.

F5 label

On magnetic disks the format 5 labels define the assigned and unassigned PAM blocks.

FDDRL job

For each FDDRL function statement, one FDDRL job is defined per individual or pubset disk. A further FDDRL job is defined for each disk set. Each FDDRL job can be executed under either the calling task (FDDRL maintask) or a separate task ( FDDRL subtask).

FDDRL request

An FDDRL request is created for each FDDRL function statement. A request has the status accepted, started or completed.

FDDRL maintask

The task which starts the program FDDRL by command /START-FDDRL is called FDDRL maintask.

FDDRL subtask

FDDRL jobs can be processed by a subtask created by FDDRL.

file expiration date

see retention period

hardware compression

This is only possible on MTC devices which are appropriately equipped. Hardware compression is performed automatically on these devices if the corresponding volume type (e.g. TAPE-C4) is used. The data is thereby compressed by the controller of the MTC device and the blocking is optimized. The capacity of the cartridges is thus better utilized.

input disk

Disk which is to be copied or saved by FDDRL.

MAREN

Software product for the management of magnetic tape cartridges in computer centers.

MAREN catalog

Central database of MAREN containing all information on the volumes. The MAREN catalog consists of the volume catalog with the archive entries and the MAREN parameter set, the secondary index files and possibly a logging file.

MAREN tape set

FDDRL is used to save a save entity (single disk or disk set) to one or more tapes. In MAREN, the tapes of a disk or disk set save are combined logically to form a tape set.

multi-mirror pair

A multi-mirror pair consists of a normal unit and an additional mirror unit.

online backup

Backup of an imported pubset.

output disk

Disk to which the input disk is to be copied or restored.

Parallel Access Volume (PAV)

Multiple I/O jobs can be executed simultaneously on a logical volume. A logical PAV is represented by a basic unit and up to three alias units.

PERCON

Software product that can be used to duplicate FDDRL saves.

pubset

Public volume set; a set of related public disks which, for example, have a common catalog. FDDRL can only process the disks of a pubset if they have been exported and are therefore exclusively available. (Exception: online backup of the HOME pubset).
A pubset is identified by a catalog ID comprising 1 to 4 characters. See also SF pubset and SM pubset.

restore

Restoration of a disk’s contents in the event of data loss due to a hardware error or inadvertent deletion. To do this FDDRL uses backup copies which were created at an earlier stage.

retention period

Period during which data cannot be modified or deleted. The physical retention period prevents backup files and volumes from being overwritten during this time. The logical retention period, which is defined by the file expiration date, prevents the modification or deletion of files.

save

Generally, writing (copying) data to a backup file.

save entity

FDDRL either saves single disks ( single disk) or combines multiple disks to form a save entity ( disk set).

save, logical

Data is read from one or more volumes and is written contiguously to one or more volumes.

save, physical

All data of a volume, including the volume labels, is written block by block to a second volume. This volume is identical to the original volume in content and structure.

SF pubset (single-feature pubset)

An SF pubset consists of a number of public disk storage units with a common catalog; it is defined by its catalog ID. An SF pubset is different from an SM pubset.

SHC-OSD

The Storage Host Component subsystem is the BS2000 host component for disk storage systems.

single disk

Save entity of FDDRL: When saving, FDDRL uses a separate tape set for a single disk or for each individual disk of a pubset.

SM pubset (system-managed pubset)

An SM pubset is a combination of several volume sets to form an addressable unit. An SM pubset is different from an SF pubset.

software compression

Before being written to backup volume, the data is compressed according to fixed algorithms and then written to the volume in this compressed form. After compression, the actual amount of data that has to be transferred is smaller, so the save run may require fewer volumes. As development of tape cartridge devices progresses, software compression is becoming increasingly less important compared to hardware compression and is consequently no longer offered in FDDRL V16.0A and higher.

tape

In the FDDRL manual, tape is used as a generic term for all real, virtual, or emulated magnetic tapes when no further distinction need be made. Volume and MTC are commonly used synonyms. Each tape must have its own unique identification (archive number, synonym: VSN).

tape set

see MAREN type set

volume

Storage medium from the perspective of BS2000. Every volume is used by BS2000. Each volume is managed by BS2000 under a unique VSN (Volume Sequence Number). The term tape or MTB is typically used in the FDDRL manual.

volume catalog

File of the MAREN catalog. The volume catalog consists of the global MAREN parameter set and archive entries containing information on every volume that is administered in MAREN.

volume set

This comprises one or more disks (volumes) with the same attributes with respect to performance behavior, allocation unit, format and availability. Several volume sets make up an SM pubset.