General Information

ionice - set or get process I/O scheduling class and priority

ionice can be used in combination with rm to remove very large files and not impact other, more high priority processes.

Available scheduling classes are:

• 0 → none (equivalent to the default of 2)
• 1 → real time - first, priority access to the disk, only available to root user
• 2 → best effort (default if not specified)
• 3 → idle - use cpu only when no other process has asked for cpu time

Priority Levels:

• 0-7
  • 0 → Highest priority
  • 7 → Lowest priority

Example of Getting the i/o scheduling class and priority of a process with PID 1637

> $ ionice -p 1637                                                                                                                                          
none: prio 0

Remove a large file, using only idle cpu time

ionice -c 3 rm /var/log/mylargelog

Remove a large file, use best effort scheduling, with a low priority

ionice -n 7 rm /var/log/mylargelog