You can cache low-priority user data blocks that are not normally stored by WAFL external cache. Low-priority blocks include blocks read in large sequential scans that are not normally reused, and blocks that have been written to the storage system through the iSCSI, NFS, or CIFS protocols.
Caching low-priority user data blocks is useful if you have workloads that fit within WAFL external cache memory and if the workloads consist of either write followed by read or large sequential reads.
You can cache low-priority user data blocks (setting flexscale.lopri_blocks to on) only if you also cache normal user data blocks (by setting flexscale.normal_data_blocks to on).
The default value is off.
Setting the option to on caches low-priority user data blocks.