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iotop(1)                        USER COMMANDS                       iotop(1)




NAME

       iotop - display top disk I/O events by process. Uses DTrace.


SYNOPSIS

       iotop   [-C]   [-D|-o|-P]   [-j|-Z]   [-d  device]  [-f  filename]  [-m
       mount_point] [-t top] [interval [count]]


DESCRIPTION

       iotop tracks disk I/O by process, and prints a summary report  that  is
       refreshed every interval.

       This is measuring disk events that have made it past system caches.

       Since  this  uses  DTrace, only users with root privileges can run this
       command.


OPTIONS

       -C     don't clear the screen

       -D     print delta times - elapsed, us

       -j     print project ID

       -o     print disk delta times, us

       -P     print %I/O (disk delta times)

       -Z     print zone ID

       -d device
              instance name to snoop (eg, dad0)

       -f filename
              full pathname of file to snoop

       -m mount_point
              mountpoint for filesystem to snoop

       -t top print top number only



EXAMPLES

       Default output, print summary every 5 seconds
              # iotop


       One second samples,
              # iotop 1


       print %I/O (time based),
              # iotop -P


       Snoop events on the root filesystem only,
              # iotop -m /

       Print top 20 lines only,
              # iotop -t 20

       Print 12 x 5 second samples, scrolling,
              # iotop -C 5 12



FIELDS

       UID    user ID

       PID    process ID

       PPID   parent process ID

       PROJ   project ID

       ZONE   zone ID

       CMD    command name for the process

       DEVICE device name

       MAJ    device major number

       MIN    device minor number

       D      direction, Read or Write

       BYTES  total size of operations, bytes

       ELAPSED
              total elapsed times from request to completion, us (this is  the
              elapsed  time  from the disk request (strategy) to the disk com-
              pletion (iodone))

       DISKTIME
              total times for disk to complete request, us (this is  the  time
              for  the disk to complete that event since it's last event (time
              between iodones), or, the time to the strategy if the  disk  had
              been idle)

       %I/O   percent disk I/O, based on time (DISKTIME)

       load   1 minute load average

       disk_r total disk read Kb for sample

       disk_w total disk write Kb for sample



DOCUMENTATION

       See  the  DTraceToolkit for further documentation under the Docs direc-
       tory. The DTraceToolkit docs may include full worked examples with ver-
       bose descriptions explaining the output.


EXIT

       iotop  will  run forever until Ctrl-C is hit, or the specified interval
       is reached.


AUTHOR

       Brendan Gregg [Sydney, Australia]


SEE ALSO

       iosnoop(1M), dtrace(1M)




version 0.75                     Oct 25, 2005                        iotop(1)

Mac OS X 10.6 - Generated Thu Sep 17 20:07:55 CDT 2009
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