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Storage > Volumes : Understanding volumes : Space savings with deduplication

Space savings with deduplication
Deduplication is an optional feature of Data ONTAP that significantly improves physical storage space by eliminating duplicate data blocks within a FlexVol volume.
Deduplication works at the block level on the active file system, and uses the WAFL block-sharing mechanism. Each block of data has a digital signature that is compared with all other signatures in a data volume. If an exact block match exists, the duplicate block is discarded and its disk space is reclaimed.
You can configure deduplication operations to run automatically or on a schedule. You can deduplicate new and existing data, or only new data, on a FlexVol volume.
To use deduplication, you must install the deduplication licenses.
Deduplication removes data redundancies, as shown in the following illustration: