The catalog entry is automatically deleted when the related file is erased. However, erasing the file contents and deleting the catalog entry can be carried out separately with the various functions of the appropriate macro or command. Erasing the file contents without deleting the catalog entry is also called “logical erasure” of the file (see "Deleting a catalog entry"), while deleting the catalog entry without releasing the storage space is called “file export” (see "Deleting a catalog entry").
The following tables show overviews of the functions of the ERASE macro and the DELETE-FILE and EXPORT-FILE commands for deleting catalog entries.
ERASE macro
Operands | Macro version number | Destroy | Deleting a catalog entry | belegten Speicherplatz freigeben | Delete logically2) | Comments |
|---|---|---|---|---|---|---|
„pathname“ | 0 – 3 | yes | yes | |||
SPACE-CATALOG | 1 – 3 | yes | yes | Default function | ||
DESTROY | 0 – 3 | yes | yes | yes | Physical data destruction | |
DATA | 0 – 3 | yes | File is “logically erased” | |||
DATA-KEEP-ATTR | 3 | yes | File-specific attributesare retained | |||
SPACE | 0 – 3 | yes | Only for pubset files | |||
CATALOG | 0 – 3 | yes | “Private” file is exported | |||
CATALOG, VOLUME | 0 | (yes) | (yes) | Volume is exported | ||
DELETE-OR-EXPORT | 1 – 3 | (yes) | (yes) | Effect depends on volume type | ||
DELETE-OR-EXPORT, VOLUME | 1 – 3 | (yes) | (yes) | Volume is exported | ||
1) If the catalog entry contains DESTROY=NO. 2) “Logical erasure” = Resetting the Last-Page Pointer | ||||||
DELETE-FILE command
Operands | Destroy | Deleting a catalog entry | Release allocated storage space | Delete | Comments |
|---|---|---|---|---|---|
FILE-NAME | yes | yes | |||
OPTION=ALL | yes | yes | Default function | ||
OPTION=DESTROY-ALL | yes | yes | yes | ||
OPTION=DATA | yes | File is “logically erased” | |||
OPTION=SPACE | yes | Only for pubset files | |||
OPTION=DATA-KEEP-ATTRIBUTES | yes | File-specific attributes are retained | |||
1) If the catalog entry contains DESTROY=NO. 2) “Logical erasure” = Resetting the Last-Page Pointer | |||||
EXPORT-FILE command
Operands | Deleting a catalog entry | Comments |
|---|---|---|
FILE-NAME | yes | File on private disk or Net-Storage volume of type NETSTOR is exported. |
EXPORT-NODE-FILE command
Operands | Deleting a catalog entry | Comments |
|---|---|---|
FILE-NAME | yes | Node file (on Net-Storage volume) is exported |
Node files are cataloged with the IMPNFIL macro or with the IMPORT-NODE-FILE command.
Erasing a file
The default function of the ERASE macro and the DELETE-FILE command depends on the type of volume. For disk files, the default value is “release allocated space and delete catalog entry”; in addition, the user can have the released space overwritten, see section"Data protection by "data destruction" (DESTROY option)"). For tape files, the default is “delete catalog entry”, which is equivalent to exporting the volume.
Destruction of data when the file is erased can be requested in the macro or command call, or can be specified previously in the catalog entry:
Operand DESTROY = YES in the CATAL macro
Operand PROTECTION...DESTROY-BY-DELETE in the CREATE-FILE and MODIFY-FILE-ATTRIBUTES commands
“Logically erasing” a file
The catalog entry and the allocated storage space are retained; the pointer to the last PAM page which was written (highest-used page) is simply reset to 0. The data still exists on the disk, but the user can no longer read it, since physical access to volumes is not permitted. The contents of the fields CRE-DATE and HIGH-US-PA in the catalog entry for a logically erased file are the same as for a file newly created by means of FILE (macro) or CREATE-FILE (command). A file may also be regarded as “logically erased” if it is (re-)opened with OPEN OUTPUT and then immediately closed again: the old file contents still exist, but the user can no longer access them. However, both in the case of OPEN OUTPUT and when erasing with the operand value DATA-KEEP-ATTR the file-specific attributes in the catalog entry are retained.
File export
The catalog entry is deleted, but the storage space and the data are retained. Files on private volumes or Net-Storage volumes of type NETSTOR can be removed from a system in this manner. They can be imported again, into the same or another system, at any time (by means of the IMPORT macro or the IMPORT-FILE command; see section "Creates a catalog entry"). Node files are imported with the IMPNF macro or with the IMPORT-NODE-FILES command.
Files are exported with the ERASE macro (DELETE-OR-EXPORT or CATALOG operand) or the EXPORT-FILE command. If the VOLUME operand is specified together with the macro operands or the command (permitted only for disk files), all files on this volume are exported.