System and method for asynchronous mirroring of snapshots at a destination using a purgatory directory and inode mapping

A computer-readable medium for updating a replica on a destination storage system, including program instructions for performing the steps of:

• reading, from changed data of the replica, identifiers related to deleted and modified logical groups of data on the replica and placing the deleted and modified logical groups in a temporary store separate from a main store of the replica;
• creating a set of references in the main store to the deleted and modified logical groups in the temporary store;
• and
• after the creating step, deallocating the temporary store while maintaining the references in the main store to the deleted and modified logical groups of data.

A system for updating a replica on a destination storage system comprising:

• means for reading, from changed data of the replica, identifiers related to deleted and modified logical groups of data on the replica and placing the deleted and modified logical groups in a temporary store separate from a main store of the replica;
• means for creating a set of references in the main store to the deleted and modified logical groups in the temporary store;
• and
• means for deallocating the temporary store, after creating the set of references, while maintaining the references in the main store to the deleted and modified logical groups of data.

A method for receiving a data stream of changed data from a snapshot on the source file system and updating a replica file system on a destination file system associated with the source file system comprising:

• reading, from the data stream, inodes related to deleted files and modified files on the replica file system and associating any read deleted files and modified files on the replica file system with a temporary directory separate from a directory tree of the replicated file system;
• reading, from the data stream, information retaining predetermined files of the deleted files and the modified files and, in response to the reading, linking the predetermined files of the deleted files and the modified files to respective new entries in the replicated file system;
• and
• when updating of the replica file system is complete, deleting the temporary directory, whereby the predetermined files of the deleted files and modified files remain associated with an updated version of the replicated file system.