Data compression is a Data ONTAP feature that enables you to reduce the physical capacity that is required to store data on storage systems by compressing the data blocks within a FlexVol volume. You can use data compression only on volumes that are created on 64-bit aggregates.
You can use data compression on primary, secondary, and tertiary storage tiers.
Data compression enables you to store more data in less space. Further, you can use data compression to reduce the time and bandwidth required to replicate data during volume SnapMirror transfers.
Data compression can save space on regular files or LUNs. However, file system internal files, Windows NT streams, and volume metadata are not compressed.
Data compression can be done in the following ways:
If in-line compression is enabled on a volume, the subsequent writes to the volume are compressed before they are written to the volumes.
If post-process compression is enabled on a volume, the new data writes to the volume are not compressed initially, but are rewritten as compressed data to the volume when data compression is run. The post-process compression operation runs as a low-priority background process.
If both in-line and post-process compression are enabled, then post-process compression compresses only the blocks on which in-line compression was not run. This includes blocks that were bypassed by in-line compression such as small, partial compression group overwrites.