What Process is using all of my disk IO

atop also works well and installs easily even on older CentOS 5.x systems which can't run iotop. Hit d to show disk details, ? for help.

ATOP - mybox                           2014/09/08  15:26:00                           ------                            10s elapsed
PRC |  sys    0.33s |  user   1.08s |                | #proc    161  |  #zombie    0 |  clones    31 |                | #exit         16  |
CPU |  sys   4% |  user     11% |  irq       0%  | idle    306%  |  wait     79% |               |  steal     1%  | guest     0%  |
cpu |  sys   2% |  user      8% |  irq       0%  | idle     11%  |  cpu000 w 78% |               |  steal     0%  | guest     0%  |
cpu |  sys   1% |  user      1% |  irq       0%  | idle     98%  |  cpu001 w  0% |               |  steal     0%  | guest     0%  |
cpu |  sys   1% |  user      1% |  irq       0%  | idle     99%  |  cpu003 w  0% |               |  steal     0%  | guest     0%  |
cpu |  sys   0% |  user      1% |  irq       0%  | idle     99%  |  cpu002 w  0% |               |  steal     0%  | guest     0%  |
CPL |  avg1    2.09 |  avg5    2.09 |  avg15   2.09  |               |  csw    54184 |  intr   33581 |                | numcpu     4  |
MEM |  tot     8.0G |  free   81.9M |  cache   2.9G  | dirty   0.8M  |  buff  174.7M |  slab  305.0M |                |               |
SWP |  tot     2.0G |  free    2.0G |                |               |               |               |  vmcom   8.4G  | vmlim   6.0G  |
LVM |  Group00-root |  busy     85% |  read       0  | write  30658  |  KiB/w      4 |  MBr/s   0.00 |  MBw/s  11.98  | avio 0.28 ms  |
DSK |          xvdb |  busy     85% |  read       0  | write  23706  |  KiB/w      5 |  MBr/s   0.00 |  MBw/s  11.97  | avio 0.36 ms  |
NET |  transport    |  tcpi    2705 |  tcpo    2008  | udpi      36  |  udpo      43 |  tcpao     14 |  tcppo     45  | tcprs      1  |
NET |  network      |  ipi     2788 |  ipo     2072  | ipfrw      0  |  deliv   2768 |               |  icmpi      7  | icmpo     20  |
NET |  eth0    ---- |  pcki    2344 |  pcko    1623  | si 1455 Kbps  |  so  781 Kbps |  erri       0 |  erro       0  | drpo       0  |
NET |  lo      ---- |  pcki     423 |  pcko     423  | si   88 Kbps  |  so   88 Kbps |  erri           0 |  erro       0  | drpo       0  |
NET |  eth1    ---- |  pcki  22 |  pcko      26  | si    3 Kbps  |  so    5 Kbps |  erri       0 |  erro       0  | drpo       0  |

  PID                   RDDSK                    WRDSK                   WCANCL                    DSK                   CMD        1/1
 9862                      0K                   53124K                       0K                    98%                   java
  358                      0K                     636K                       0K                     1%                   jbd2/dm-0-8
13893                      0K                     192K                      72K                     0%                   java
 1699                      0K                      60K                       0K                     0%                   syslogd
 4668                      0K                      24K                       0K                     0%                   zabbix_agentd

This clearly shows java pid 9862 is the culprit.


You're looking for iotop (assuming you've got kernel >2.6.20 and Python 2.5). Failing that, you're looking into hooking into the filesystem. I recommend the former.


To find out which processes in state 'D' (waiting for disk response) are currently running:

while true; do date; ps aux | awk '{if($8=="D") print $0;}'; sleep 1; done

or

watch -n1 -d "ps axu | awk '{if (\$8==\"D\") {print \$0}}'"

Wed Aug 29 13:00:46 CLT 2012
root       321  0.0  0.0      0     0 ?        D    May28   4:25  \_ [jbd2/dm-0-8]
Wed Aug 29 13:00:47 CLT 2012
Wed Aug 29 13:00:48 CLT 2012
Wed Aug 29 13:00:49 CLT 2012
Wed Aug 29 13:00:50 CLT 2012
root       321  0.0  0.0      0     0 ?        D    May28   4:25  \_ [jbd2/dm-0-8]
Wed Aug 29 13:00:51 CLT 2012
Wed Aug 29 13:00:52 CLT 2012
Wed Aug 29 13:00:53 CLT 2012
Wed Aug 29 13:00:55 CLT 2012
Wed Aug 29 13:00:56 CLT 2012
root       321  0.0  0.0      0     0 ?        D    May28   4:25  \_ [jbd2/dm-0-8]
Wed Aug 29 13:00:57 CLT 2012
root       302  0.0  0.0      0     0 ?        D    May28   3:07  \_ [kdmflush]
root       321  0.0  0.0      0     0 ?        D    May28   4:25  \_ [jbd2/dm-0-8]
Wed Aug 29 13:00:58 CLT 2012
root       302  0.0  0.0      0     0 ?        D    May28   3:07  \_ [kdmflush]
root       321  0.0  0.0      0     0 ?        D    May28   4:25  \_ [jbd2/dm-0-8]
Wed Aug 29 13:00:59 CLT 2012
root       302  0.0  0.0      0     0 ?        D    May28   3:07  \_ [kdmflush]
root       321  0.0  0.0      0     0 ?        D    May28   4:25  \_ [jbd2/dm-0-8]
Wed Aug 29 13:01:00 CLT 2012
root       302  0.0  0.0      0     0 ?        D    May28   3:07  \_ [kdmflush]
root       321  0.0  0.0      0     0 ?        D    May28   4:25  \_ [jbd2/dm-0-8]
Wed Aug 29 13:01:01 CLT 2012
root       302  0.0  0.0      0     0 ?        D    May28   3:07  \_ [kdmflush]
root       321  0.0  0.0      0     0 ?        D    May28   4:25  \_ [jbd2/dm-0-8]
Wed Aug 29 13:01:02 CLT 2012
Wed Aug 29 13:01:03 CLT 2012
root       321  0.0  0.0      0     0 ?        D    May28   4:25  \_ [jbd2/dm-0-8]

As you can see from the result, the jdb2/dm-0-8 (ext4 journal process), and kdmflush are constantly block your Linux.

For more details this URL could be helpful: Linux Wait-IO Problem