Recall on file access

Recalling migrated files has the following repercussions:

• The recall is initiated implicitly when the file is opened. This is possible for any file.

• Recalling takes a certain amount of time, depending on the current system and device loads and on the type of background storage used (disks in the case of S1, magnetic tape cartridges S2).

• This means that processing in a user application can be interrupted (i.e. delayed) at a number of points (whenever a file is opened).

• The background storage is accessed every time a recall request is issued. In particular for migration to S2, implicit recalls can considerably increase the mount rate, which usually leads to a corresponding increase in runtime.