If the working set of the storage system is very large, such as a large e-mail server, you can cache only system metadata in WAFL external cache memory by turning off both normal user data block caching and low-priority user data block caching.
When you cache only system metadata, with both flexscale.normal_data_blocks and flexscale.lopri_blocks set to off, WAFL external cache interprets this setting as the buffer cache policy of reuse and does not save normal data blocks or low-priority blocks in the external cache.
These commands are available through the nodeshell. You access the nodeshell by using the system node run command. For more information, see the man page.