Patent ID: 8639665

Claim:
A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to: perform pre-migration to migrate committed resident files to off-line storage in a hierarchical storage management (HSM) file system; responsive to initiating a hybrid metadata image backup and backup operation, perform a metadata image backup of the HSM file system, wherein the metadata image backup backs up file system metadata to create a point-in-time image of the HSM file system; concurrent with performing the metadata image backup of the HSM file system, identify a set of resident tiles that are not yet migrated to off-line storage in the HSM file system; identify immutable files within the set of resident files to form an optimized set of resident files; and pass the optimized set of resident files to a backup system, wherein the backup system backs up file data for the optimized set of resident files.