Patent ID: 8458131

Claim:
At a backup server, a method being performed on a computer processor for de-duplicating backup data in storage managed by the backup server, said method comprising: accessing a first client backup database from storage managed by the backup server, said first client backup database storing a first one or more blocks of data, said first one or more blocks of backup data previously stored in said first client backup database to back up said first one or more blocks of backup data for a first client; accessing a second different client backup database from storage managed by the backup server, said second client backup database storing a second one or more blocks of backup data, said second one or more blocks of backup data previously stored in said second client backup database to back up said second one or more blocks of backup data for a second different client; comparing hash values for blocks in said first one or more blocks to hash values for blocks in said second one or more blocks to identify a common block, including: determining that said common block is included in said first one or more blocks of backup data; and determining that said common block is included in said second or more blocks of backup data; and in response to identifying said common block, de-duplicating said common block by: storing said common block in a common backup database, said common backup database in storage managed by the backup server; inserting a pointer into said first client backup database, said pointer referencing the common block in said common backup database; inserting said pointer into said second client backup database; removing said common block from said first client backup database; and removing said common block from said second client backup database.