vSAN performs block-level deduplication and compression to save storage space. This allows you to make more efficient and cost-effective use of storage in your VMware Cloud on AWS SDDC.

Deduplication removes redundant data blocks. Compression removes additional redundant data within each data block. Compression alone or compression and deduplication together reduce the amount of physical storage required to store the data. VMware vSAN applies deduplication followed by compression as it moves data from the cache tier to the capacity tier.

Deduplication and compression are automatically enabled for VMware Cloud on AWS clusters containing i3 hosts. These features cannot be turned off. Clusters containing i3en or i4i hosts are automatically enabled for compression only. Enabling compression without deduplication improves performance.

Deduplication in vSAN occurs inline when data is written back from the cache tier to the capacity tier. The deduplication algorithm uses a fixed block size and is applied within each disk group. Redundant copies of a block within the same disk group are deduplicated.

Storage savings resulting from deduplication and compression are highly dependent on the workload data. On average, storage space savings using compression are in the range of 1.5X to 2X. Used in conjunction with deduplication, the savings may be higher.