解决 Log output is incomplete or unavailable 问题

最近遇到一件很奇怪的事情，那就是systemctl status xxx总是无法正常显示journal日记，提示

Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.

后来才发现是journalctl这逼给删掉了，journal会统计日记大小，到了某种程度就自动删掉

解决办法很简单

journalctl --vacuum-size=1G

最大可存放1GB journal，搞定了