Check high disk I/O commands:

  1. iotop -oPa -d 2: High I/O on /var partition
  2. glances: High iowait and load
  3. iostat -2/var high I/O confirmation
  4. ls -lhS /var/log/*log | head: Large mail.log
  5. tail -f /var/log/mail.log: Rapid, continuous logging