Patent ID: 8140786

Claim:
A system for rebuilding at least a portion of a signature database that reflects contents of an archive copy of a data set, comprising: a signature component, wherein the signature component generates a substantially unique identifier for all data objects within the data set and stores the substantially unique identifiers in a signature database, wherein the substantially unique identifier for a data object reflects contents of the data object; an encryption component, wherein the encryption component encrypts at least some of the data objects of the data set; a copy component, wherein the copy component: uses the generated substantially unique identifiers to identify redundant data objects in the data set and deduplicate the redundant data objects in order to create a deduplicated archive copy of the data set that comprises the encrypted data objects; wherein the archive copy is physically stored on sequential media; and stores the archive copy as one or more data chunks stored on the sequential media, wherein each chunk is stored with header information that includes at least one substantially unique identifier; and stores information related to locations of the encrypted data objects on the sequential media in a location database separate from the signature database; and a database rebuilding component, wherein the database rebuilding component: receives an indication that the signature database is unrecoverable or unavailable; accesses header information of at least one chunk in order to determine at least one substantially unique identifier within the header information; and uses the determined at least one substantially unique identifier from the header information in order to rebuild at least part of the signature database.