Datbase keeps Database keeps track of the number of times a storage location on User disk is referenced by virtual volumes Virtual volume "metadata" files, stored on Meta Data LUN's, track where logical blocks were stored on the User disk User data, written by Backup Applications, stored in locations on "User Data" RAID LUN's S1 S2 ... ... ... DB1: S1 DB25: DB26: DB27: DB28: S1 S3 S56 S57 V00004 Metadata File S3 T rack S79 S78 S 77 S7 6 DB91: DB92 : DB 93: DB 94: S62 S3 S63 S4 V00003 Metadata File S4 DB109: DB110: DB111: DB112: S21 S3 S23 S24 V00002 Metad ata File DB 2: S2 DB3: S3 DB 4: S4 V00001 Metadata File "User Data" (MD) RAID LUN Database Sector S1 S2 S3 S4 Ref. Count 2 1 4 2 "Meta Data" (MD) RAID LUN Figure 6-6 HyperFactor deduplication The capacity of the ProtecTIER Repository consists of the factored backup streams and the metadata that describes the factored backup streams, so it is fundamental to have the proper amount of back-end disk capacity as part of the ProtecTIER System configuration. The capacity reduction effect of deduplication is expressed as a deduplication ratio or factoring