FreeBSD ARC accounting explains apparent memory exhaustion

Category: Engineering post
Status: discussion
Sources: crocidb post, HN discussion
Summary: A debugging write-up traces apparent FreeBSD memory exhaustion to how the ZFS ARC and the reporting tools account for cache memory, explaining why free memory looks alarmingly low while the system is healthy. The post walks through the measurement tools and the difference between wired ARC memory and true pressure.
Why it matters: It is a concrete field guide for operators reading FreeBSD and ZFS memory metrics, where cache accounting routinely reads as exhaustion.