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The Data file contains all the data about any volume or dataset. In Control‑M/Tape, unlike other tape management systems, volume information and dataset information are stored in the same file, but with different record types and formats.
The following table lists the two most common record types in the Control‑M/Tape Data file:
Table 225 Common Data File Record Types
Record Type |
Description |
|---|---|
Volume record |
Contains information regarding a volume. |
Dataset record |
Contains information regarding a dataset. |
Note: Additional record types and formats in the database are not described because they are not relevant for most users.
Volume and dataset records are mapped using assembler macros CTTDVL and CTTDDS, respectively. All record types in the Data file have a common header at the beginning of the record. This header contains the following information about the record:
Figure 75 Sample Record in the Data File
Table 226 Fields in the Data File Record
Record |
Description |
|---|---|
RBA
|
Internal record location identifier (explained later in this chapter). Each record in the Data file is assigned an RBA that indicates the location of the record in the Data file. The format of the Control‑M/Tape RBA is ebbr. The first byte identifies the extent file number, the next two bytes identify the block number in the Data file, and the last byte identifies the record number in that block. Access to a specific Data file record can be performed using its RBA if known (or using the index, as explained later in this chapter). Access of a data record using its RBA is known as "non‑keyed access". |
Record Status Indicator |
Indicates whether the record is active or free. |
Record Type |
Indicates whether the record is a volume or dataset record. |
Record Level |
Used internally by Control-M/Tape to identify the level of the record. |
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