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Data compression and deduplication

Beginning with Data ONTAP 8.0.1, data compression is supported with deduplication.

When both data compression and deduplication are enabled on a FlexVol volume, the data is first compressed and then deduplicated. Therefore, deduplication can further increase the space savings by removing duplicate blocks in the FlexVol volume.

Though data compression and deduplication can be enabled on a FlexVol volume, the savings might not be the sum of the savings when each is run individually on a data set. The combined savings can yield higher savings than running deduplication or data compression individually.

You can achieve better savings when you run the data compression scanner before deduplication. This is because data compression scanner cannot run on data that is locked by deduplication, but deduplication can run on compressed data.

The following illustration shows how data is first compressed and then deduplicated:

When you run deduplication on a FlexVol volume that contains uncompressed data, it scans all the uncompressed blocks in the FlexVol volume and creates a digital fingerprint for each of the blocks.

Note: If a FlexVol volume has compressed data, but the compression option is disabled on that volume, then you might lose the space savings when you run the sis undo command.