Migration types

You can configure migration jobs and threshold migration. You can selectively migrate files that are specified in a list file.

Migration jobs and list migrations specify which files can be migrated, but they do not consider the space capacity of the volume. Threshold migration controls space usage of the volume, but allows less control of which files are migrated.

Migration jobs

A migration job defines a set of files and their migration behavior. When you run the job, the files that are specified in the job are copied to IBM® Storage Protect storage.

A migration job can replace the original file with a stub file, delete the original file, or do nothing to the original file. You configure the action. You configure whether files are backed up before migration.

You can start the migration job immediately with the HSM for Windows™ client GUI or with an HSM for Windows client command from a Command Prompt window. You can also start the migration job later with a scheduling program acquired from another vendor.

List migrations

A list migration migrates the files that are listed in a text file. A list migration is not affected by disk-space usage or the age and size of files.

A list migration can replace the original file with a stub file, delete the original file, or do nothing to the original file. You configure the action. You configure whether files are backed up before migration.

Start a list migration with the HSM for Windows client dsmclc migratelist command.

Threshold migration

Threshold migration provides migration that is based on space usage. When the used space on a volume reaches a high threshold, migration begins automatically. Files are migrated to free up space until used space falls to a low threshold. The files that are migrated meet a minimum age and size, and are prioritized for migration. Less dynamic and larger files are migrated before more dynamic and smaller files. With proper configuration, threshold migration can automatically prevent the volume from running out of space.

Threshold migration replaces the original file with a stub file. You configure whether files are backed up before migration.

Configure threshold migration with the HSM for Windows client dsmhsmclc configurethresholdmig command.

The following table summarizes the similarities and differences between migration jobs, list migrations, and threshold migration.

Table 1. Migration jobs compared to threshold migrationThe table is a summary of differences and similarities between migration jobs, list migrations, and threshold migration.

Criterion	Migration job and list migration	Threshold migration
Which files are migrated?	Migration job: You configure the path, type (file extension), minimum age, and minimum size of files to migrate. All files that meet the criteria are migrated. List migration: The files are identified in a list file.	You configure the minimum file age and minimum file size, and the importance of file age relative to file size. HSM for Windows client creates a ranked list of migration candidates that are based on the criteria. Files from this list are migrated as needed to meet the space usage targets.
When does migration occur?	You start migration manually, or with a scheduling tool that is provided by another vendor.	HSM for Windows client automatically starts migration when it detects that space usage on the volume reaches the high threshold.
When does migration end?	Migration job: Migration ends when all files that meet the criteria are migrated. List migration: Migration ends when all files in the list are migrated.	Migration ends when space usage on the volume reaches the low threshold, or when there are no more candidates for migration.
What remains on the volume from which the files were migrated?	HSM for Windows client can do one of three things, as you configure: Replace the original file with a stub file Leave the original file Delete the original file, create no stub file.	HSM for Windows client replaces the original file with a stub file.
When are files automatically recalled to the originating file system?	If the file system requests an operation that cannot be satisfied by the stub file, the migrated file is automatically and transparently recalled. The stub file provides the information to recall the file.	If the file system requests an operation that cannot be satisfied by the stub file, the migrated file is automatically and transparently recalled. The stub file provides the information to recall the file.
Can I selectively retrieve the migrated files?	Yes, by using the HSM for Windows client GUI or the dsmclc retrieve command.	Yes, by using the HSM for Windows client GUI or the dsmclc retrieve command.
Can I selectively recall the migrated files?	Yes, if a stub file exists on the file system. Use the dsmclc recall command or the dsmclc recalllist command.	Yes, if a stub file exists on the file system. Use the dsmclc recall command or the dsmclc recalllist command.