The server disk is not full, but the service cannot write logs. Here's how I investigated:

I once encountered a puzzling problem while on duty: the application reported that it could not write logs, but df -h showed that the disk still had 30% of space available, and restarting the service did not work. The development team thought it was a permission issue, but the operations team found that the directory permissions were normal. Later, I used df -i to discover that the inodes were…