The CA Disk catalog management hook uses CSECT ADSAR010 as part of module IGG026DU, and ADSHS001 as part of the module IGX00024. The CA Disk F1-DSCB missing exit uses CSECT ADSAR004 as part of module IFG0EX0A. After installing the appropriate modules, you have the following conceptual arrangement. The following illustration is a sample Auto‑Restore Method:
The previous illustration shows that control is passed from the user doing a catalog locate to the catalog management hook and then to either the DFHSM hook or a dummy module. From there, control is passed to catalog management. Catalog management performs its specified function and returns control to the next module up the chain, giving DFHSM a chance to auto recall the data set if appropriate. DFHSM returns control to the next module up the chain. Note that if the dummy module is installed, it just returns control up the chain without any other processing.
CA Disk now gets control. If DFHSM had successfully recalled the data set, it now appears to CA Disk that the data set exists on a real volume. If the data set is cataloged to the CA Disk pseudo volume, CA Disk takes one of two actions. If the program issuing the SVC 26 is recognized as one that needs the special handling provided by the CA Disk DFHSM SVC hook, it returns a volser of MIGRAT. If CA Disk does not recognize the calling program, CA Disk attempts to auto-restore the data set by using the DMSAR started task. If either DFHSM or CA Disk auto-restored the data set, it appears to the user that the data set exists on a real volume.
This design allows auto-restores from either the CA Disk archives or DFHSM migration volumes on the same system without interference. Other software products such as CA Allocate and CA ACF2 also front- and back-end catalog management.
The illustration shows that control is passed from the user invoking a DFHSM Auto Recall to the DFHSM SVC hook. Then, control is passed to the catalog management hook. From this point on, the catalog management hook process is as documented above. When the auto-restore is complete, control is returned to the DFHSM SVC hook. If the data set was not archived by CA Disk, control is passed to the DFHSM SVC for its own Auto Recall processing.
Again, by examining the illustration you can see that if the F1-DSCB missing exit is invoked, CA Disk gets control first in its exit as CSECT ADSAR004 of module IFG0EX0A. If it cannot restore the data set, it calls the CSECT IFG0EX0A to attempt the restore before returning to the user.
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