A method for concurrent data migration includes classifying files to be migrated
into plural jobs, selecting media to which to migrate each job, and using plural
drives concurrently to write the jobs to the media. The selection of a medium is
performed in a way that prevents the number of writeable media from exceeding the
number of available drives, unless no allocated medium has sufficient space to
store any files in a migration job. A medium is preferentially selected that has
already been allocated for writing, has space to store at least one file in the
job, is not in use for another job, and can be robotically mounted on a drive.
If such a medium does not exist, then the set of available media is canvassed to
locate an alternative medium. The attributes of each medium are evaluated to determine
which medium can be selected most consistently with the goals of (1) preventing
the number of media from exceeding the number of drives, and (2) providing sufficient
media to allow plural drives to be used concurrently. The technique can be embodied
in a file management environment that transparently migrates files meeting certain
criteria and stores the location of the migrated file in a reparse point provided
by the file system.
