Primary stub file retention and secondary retention coordination in a hierarchical storage system

摘要

A protected file is retained in secondary storage for a retention period, and a corresponding stub file is retained in primary storage for the retention period. The stub file retains attributes of the file indicating a location of the file data in the secondary storage and indicting that the stub file is to be retained for the retention period. A system administrator may instruct a primary file server that a secondary file server supports retention based protection and it is desired to protect stub files corresponding to protected files that are migrated to the secondary file server. The primary file server may request the secondary file server to return a protection status of the file after migration. This enables automatic policy-based migration to both file level retention (FLR) and non-FLR retention protected secondary storage from diverse applications accessing FLR or non-FLR files in the primary storage.