Patent ID: 8082227

Claim:
A method, comprising: initiating a backup operation; detecting a first hard link for primary data and a second hard link for the primary data and backing up the first and second hard links within a link data structure associated with the backup operation and backing up the primary data once; and encountering a third hard link for a modified version of the primary data during the backup operation and backing up the third hard link within the data structure and backing up the modified version of the primary data as a session-specific version of the primary data by describing changes of the modified version in metadata and using the metadata as the session-specific version of the primary data, the metadata represents the primary data that is altered via the changes during the backup operation and before the backup operation has a chance to conclude, the link data structure includes a same identifier for the primary data and the modified version of the primary data, the same identifier stored in an single entry within the linked data structure and the entry includes a list of additional information including the first hard link, the second hard link, and the third hard link, the third hard link including a pointer to the metadata, the linked data structure includes hashed entries, each hashed entry representing particular primary data as a chain of additional data structures, and each additional data structure having: a particular identifier for the particular primary data, a particular file system identifier for a file system of the particular primary data, a link count that identifies a total number of links that point to a particular hard link for the hashed entry, and a next pointer for a next additional data structure in the chain for the hashed entry.