The FreeBSD operating system collects statistical data from the ZFS subsystem using mechanisms originating from the OpenSolaris kstat framework.
This data is stored in sysctl variables (sysctl kstat.zfs). I have been recently working on improving a script named arc_summary.pl that was originally written by Ben Rockwood and modified by Jason J. Hellenthal. I have rewritten large parts of this script and renamed it to zfs-stats, as it’s output is not limited to ARC anymore.
The zfs-stats script now displays some general ZFS information and human-readable ZFS statistics about the following subsystems:
- zfetch (DMU)
- vdev cache