The aspects described below merely serve for application runtime optimization and may otherwise be ignored. The relevant procedure is recommended, however, to reduce the overall system load.
Checking/ensuring the existence of a file should be effected using the SECURE-RESOURCE-ALLOCATION command rather than the commands SHOW-FILE-ATTRIBUTES or ADD-FILE-LINK.
Before processing is started, a check should be made for all files to be subsequently opened for reading to ensure that their data is actually present on the processing level; this is done with the aid of a SECURE-RESOURCE-ALLOCATION command with specification of a wait time. A positive side effect of this is that several files are recalled by one request, which can relieve the load on the system (see above).
If deletion of a file is to cause its data to be overwritten (DESTROY operand), this should be defined as an attribute of the file (MODIFY-FILE-ATTRIBUTES command) and not only when the file is actually deleted (DELETE-FILE command). Otherwise deletion of the data within the framework of migration will not overwrite the data.
If the retention period for a file migrated to S2 is changed, availability of the corresponding data during that interval cannot be guaranteed. A previous recall is therefore recommended.