FreeBSD 12 – Common Problem 014 – /var Fills Up from Unbounded Log Growth

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Disk-full conditions prevent writes, package operations, and daemon startup.

Environment & Reproduction

Verbose debug logging or crash loops create multi-GB logs in `/var/log`.

Root Cause Analysis

Missing/incorrect `newsyslog.conf` rotation policy allows unlimited file growth.

Quick Triage

Locate largest files quickly.

df -h /var
du -xhd 1 /var | sort -h
ls -lh /var/log | tail

Step-by-Step Diagnosis

Validate active rotation config and offending service verbosity.

grep -v '^#' /etc/newsyslog.conf
newsyslog -nv
service syslogd status

Solution – Primary Fix

Rotate logs immediately and set strict retention policy.

newsyslog -F
service syslogd restart
truncate -s 0 /var/log/daemon.log

Solution – Alternative Approaches

Move high-volume logs to dedicated ZFS dataset with quotas and compression.

Verification & Acceptance Criteria

`df -h` shows safe free space and logs rotate on schedule without errors.

Rollback Plan

Restore previous rotation config if required and recover archived logs from backup.

Prevention & Hardening

Set volume alerts at 70/85/95% and enforce app log level defaults in production.

Related Errors & Cross-Refs

`No space left on device`, failed pidfile creation, package DB update failures.

Related tutorial: View the step-by-step tutorial for freebsd-12.

View all freebsd-12 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

`newsyslog.conf(5)`, `syslogd(8)`, FreeBSD logging practices.