When you add disks to a Virtual SAN cluster with enabled deduplication and compression, specific considerations apply.
You can add a capacity disk to a disk group with enabled deduplication and compression. However, for more efficient deduplication and compression, instead of adding capacity disks, create a new disk group to increase cluster storage capacity.
When you remove a disk form a cache tier, the entire disk group is removed. Removing a cache tier disk when deduplication and compression is enabled triggers data evacuation.
Deduplication and compression is implemented at a disk group level. You cannot remove a capacity disk from the cluster with enabled deduplication and compression. You must remove the entire disk group.
If a capacity disk fails, the entire disk group becomes unavailable. To resolve this issue, identify and replace the failing component immediately. When removing the failed disk group, use the No Data Migration option.