Stub files
A stub file is created on the file system from which a file is migrated. The stub file contains information for the HSM for Windows™ client to recall the original file to the file system.
A stub file contains the same recall information whether it was created by a migration job, a list migration, or a threshold migration.
When you or a Windows application accesses a migrated
file stub, the HSM for Windows client automatically recalls
the file from IBM Storage Protect storage. This automatic recall is
called transparent
recall.
Restriction: If
only the Windows alternate data stream (ADS) data in a stub
file is accessed or modified, the file is not recalled. When a file is recalled because the primary
data stream (PDS) data is accessed in the stub file, the ADS data is not recalled. The ADS data is
stored in the stub file on the file system and does not change when the PDS data is
recalled.
A stub file looks and acts like a regular file on the file system,
with a few exceptions:
- Files that are migrated are marked.
- In the Windows Explorer, a migrated file has an overlay icon.
- On a Command Prompt window, a migrated file is enclosed in brackets.
- Access to migrated files can be slower, if the file operation recalls the migrated file from IBM® Storage Protect storage.
When a file is migrated, the last access time of the file does not change.
You can selectively recall a file from IBM Storage Protect storage if a stub file exists on the file system.