gtpd1m2s | Database Reference |
The validation and reconstruction of collections currently provided by
TPFCS by options on the ZBROW command can currently operate only on
extended-resident collections. An error message results if you enter
the ZBROW command with either the VALIDATE or RECONSTRUCT parameter specified
for a compact-resident collection.
The following describes the scope of validation that TPFCS currently
provides on extended-resident collections by using the ZBROW command:
- Validation currently does not perform automatic reconstruction or
correction of errors reported, and reconstruction does not perform any
preliminary validation of a collection.
- A subset and not all of the fields in the StructureDasd object are
verified for those collections when validation is performed.
- The allocated and released data, key, and directory chains are verified
when validation is performed.
- When validation is performed, an attempt is made to verify all directory
entries, including those embedded in the StructureDasd object.
- Other than validation of directory entries, validation does not verify the
contents of records on the data, key, and directory chains.
- Validation ends as soon as a major error occurs. As a result, a
given validation report resulting in a response to a ZBROW command with the
VALIDATION parameter might not indicate all of the errors present in a
collection. It might be necessary for you to enter a validation
request, followed by a reconstruction request or manual reconstruction,
followed by another validation request. Depending on the nature of the
errors found, you might have to use the ZBROW command several times,
alternating between validation and reconstruction requests.
The following describes the scope of reconstruction that TPFCS currently
provides on extended-resident collections by using the ZBROW command:
- Reconstruction does not perform any preliminary validation of a
collection.
- The ZBROW command can only be used to perform one of the following types
of reconstruction at any given time:
- Reconstruction of the allocated data chain using information from key
records located on the allocated key (index) chain (when present), and the
directory entries located in the structure object as well as those located in
the records on the allocated directory chain.
- Reconstruction of the allocated key chain (when present) using information
from the allocated data chain as well as the collection directory
entries.
- Reconstruction of both the allocated directory chain and the allocated key
chain (when present) using information from the allocated data chain.
- Note:
- TPFCS can automatically rebuild even those allocated chains it uses to
perform a given reconstruction operation before that operation has been
completed.
- Reconstruction of the data chain normally does not change the contents of
data records. Records are either placed on the new data chain or
excluded from it.
For information about the ZBROW command, see TPF
Operations.