The following activities must be carried out when introducing migration:
The migration function cannot be used for all files. The HSMS administrator should observe the notes in section "Except file", and all users should observe the notes in section "File migration inhibit".
Please note that in many cases the files stay migrated for a long period of time. It is recommended to only migrate files that have already been saved (this is ensured by the HSMS parameter MIGRATION-CONTROL(BACKUP-MANDATORY=*YES), however, these backups become obsolete after the retention period expires and are deleted from the backup archive (//MODIFY-ARCHIVE SAVE-FILE=*DELETE). From this point in time, there is no existing copy of the file.
Therefore migrated files should be backed up from time to time, if the backup timeframe allows it: BACKUP-FILES ... SAVE-OPTIONS=*PARAMETERS(SAVE-DATA=*S2-S2-S0). This ensures that there are always copies of the data of all storage levels. Version backup can also be used for the purpose.
Aside from this, HSMS should be started as soon as possible after system initialization to ensure that the files are recalled as quickly as possible.
Jobs which previously used /SHOW-FILE-ATTRIBUTES or /ADD-FILE-LINK to check the presence of files needed during the program run should use /SECURE-RESOURCE-ALLOCATION with a wait time instead (see section "Implicit recall on file access").
Applications which use the internal file name (CFID) for checking and processing files (e.g. UPAM), must take the following into account: comparing the catalog entry before and after OPEN is not permitted, since opening on a migrated file recalls the latter, thereby changing the internal file name (CFID). If an FSTAT macro is issued before processing, the catalog entry should not be noted for a check. It is better to use /SECURE-RESOURCE-ALLOCATION with a wait time, since this will recall the file.
For the SYSHSMS user ID, the storage space (PUBLIC-SPACE-LIMIT) should not be limited if very large files are recalled implicitly. When it is recalled, the file is first imported to the storage space of the SYSHSMS user ID on the pubset on which it was located prior to migration before the assignment is changed to the final user ID. When creating the SYSHSMS user ID, the storage space extension (PUBLIC-SPACE-EXCESS) should therefore be allowed.
Note
The appendix contains summarized information which all users should receive before the migration function is introduced. The restriction on reproduction therefore does not apply to the appendix. The system administrator can distribute copies of the appendix to future users and/or users affected by the migration function.