“The server feels slow.” It is the most common ticket text in the world, and the least useful. Before you can fix anything you need to know whether the box is CPU bound, memory pressured, waiting on disk, saturating a NIC, or simply running a runaway process in one jail that is starving everyone else. On jail hosts, the second half of the problem is attribution: not just what is overloaded, but which jail is responsible. FreeBSD ships with an unusually complete troubleshooting toolkit out of the box. This article is a practical tour: how to watch CPU, memory, disk, and network in real time, how to drill from a host-level symptom down to the process responsible, and how to use kern.racct and rctl to both measure and cap what individual jails consume. A short closing section points at jail_exporter for those who want long-term Prometheus data, but the focus here is the in-box troubleshooting toolkit. This article intentionally sticks to tools present in the FreeBSD base system. There is…
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