Patent ID: 7599971

Claim:
In a distributed computing system having a primary storage device, a secondary storage device and a policy engine server, the policy engine serve being configured to manage migration of files between the primary and secondary storage devices by migrating data files on the primary storage device to the secondary storage device and replacing the data files on the primary storage device with placeholder files, a method for locating placeholder files within the primary storage device that are not properly referenced by secondary files stored on the secondary storage device, the method comprising: identifying a placeholder file on a primary storage device that has replaced a data file, the placeholder file including an offline reference to the data file stored as a secondary file on the secondary storage device, wherein the offline reference includes file identification data including a content address of the secondary file and the file identification data describes the data file; identifying the secondary file on the secondary storage device using the content address of the secondary file included in the offline reference of the placeholder file; identifying an online reference included in the secondary file, wherein the online reference includes an address to a particular placeholder file stored on the primary storage device; determining that the placeholder file is a missing parent when the address to the particular placeholder file does not identify the placeholder file; and notifying a user of the policy engine server when the online reference of the secondary file does not properly reference the placeholder file.