====== iotop ======
---- dataentry analysisTool ----
name           : iotop
features_ttags : monitoring, application usage
layers_ttags   : application, operating system, block device, network
version        : 0.6 (2013-05-26)
webpage_url    : http://guichaz.free.fr/iotop/
license_ttag   : GNU GPL
----


iotop is a tool to monitor I/O usage, it works with the Linux kernel starting at version 2.6.20.
By default iotop works on a per-thread basis and shows information for each thread individually.
//This tool requires root access.//
===== Usage =====
For the use case of analyzing a single program iotop offers the option to limit diagnostics to a single process. Replace ''PID'' with your process-id. 
<code bash>
iotop -p PID
</code>
While running in interactive mode you can toggle between showing all threads and only those doing I/O by pressing ''o''.

For analyzing a single programs performance you might want to log the results instead of viewing them in interactive mode. Use the '--batch' or '-b' option and log the results to a file.
<code bash>
iotop -bp PID > iostats.log
</code>
===== Sample Output =====
By default the tool shows disk read- and write speed per thread as well as the percentage of time spent waiting for swap and I/O. The I/O priority is also displayed. 

Below you see part of the output of ''iotop'' while running ''cat /dev/urandom > random.file''.

<code>
Total DISK READ :0.00 B/s | Total DISK WRITE :13.45 M/s
Actual DISK READ:0.00 B/s | Actual DISK WRITE:0.00 B/s
TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND
4879 be/4  someuser 0.00 B/s   13.45 M/s   0.00 %     0.00 % cat /dev/urandom
1    be/4  root     0.00 B/s   0.00 B/s    0.00 %     0.00 % init
2    be/4  root     0.00 B/s   0.00 B/s    0.00 %     0.00 % [kthreadd]
</code>


===== Similar tools =====

---- datarelated ----
cols  : features, layers
max   : 5
sort  : ^name
----