K: Kilobyte
M: Megabyte
G: Gigabyte
%: 1/100
Active: number of bytes active
Inact: number of bytes inactive
Wired: number of bytes wired down, including BIO-level cached file data pages
Cache: number of clean bytes caching data that are available for immediate reallocation
Buf: number of bytes used for BIO-level disk caching
Free: number of bytes free
Total: number of wired bytes used for the ZFS ARC
MRU: number of ARC bytes holding most recently used data
MFU: number of ARC bytes holding most frequently used data
Anon: number of ARC bytes holding in flight data
Header: number of ARC bytes holding headers
Other miscellaneous ARC bytes
Total: total available swap usage
Free: total free swap usage
Inuse: swap usage
In: bytes paged in from swap devices (last interval)
Out: bytes paged out to swap devices (last interval)