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Total DISK READ: 1056.26 K/s | Total DISK WRITE: 9.20 M/s
  TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND
 1055 be/4 root          0.00 B     11.64 M  0.00 %  1.99 % [kjournald]
 1054 be/4 root          0.00 B      9.72 M  0.00 %  1.70 % [kjournald]
 1053 be/4 root          0.00 B      5.21 M  0.00 %  0.73 % [kjournald]
 1056 be/4 root          4.00 K      2.77 M  0.00 %  0.39 % [kjournald]
 1082 be/4 root          0.00 B      0.00 B  0.00 %  0.34 % [flush-8:48]
 1078 be/4 root          0.00 B      0.00 B  0.00 %  0.33 % [flush-8:32]
 1080 be/4 root          0.00 B      0.00 B  0.00 %  0.09 % [flush-8:16]
  493 be/3 root          0.00 B   1128.00 K  0.00 %  0.04 % [jbd2/sda3-8]
 1081 be/4 root          0.00 B      0.00 B  0.00 %  0.01 % [flush-8:64]
 1079 be/4 root         16.00 K    228.00 K  0.00 %  0.01 % [flush-8:0]
 1126 be/4 root          0.00 B      0.00 B  0.00 %  0.00 % [kjournald]
 1125 be/0 root          0.00 B     56.00 K  0.00 %  0.00 % [loop0]
 2974 be/4 nobody        4.00 K     12.00 K  0.00 %  0.00 % httpd -k start -DSSL
 5506 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  301 be/4 nobody        0.00 B      8.00 K  0.00 %  0.00 % httpd -k start -DSSL
  311 be/4 nobody        0.00 B      8.00 K  0.00 %  0.00 % httpd -k start -DSSL
  314 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  332 be/4 nobody        0.00 B      8.00 K  0.00 %  0.00 % httpd -k start -DSSL
24916 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  347 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  348 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
16741 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  367 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  368 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  384 be/4 nobody        0.00 B     12.00 K  0.00 %  0.00 % httpd -k start -DSSL
  394 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  414 be/4 nobody        0.00 B     12.00 K  0.00 %  0.00 % httpd -k start -DSSL
  421 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  422 be/4 nobody        0.00 B      8.00 K  0.00 %  0.00 % httpd -k start -DSSL
21049 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
29281 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
29289 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
 3517 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
29389 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
29390 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
29398 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
32207 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL
  874 be/4 nobody        0.00 B      8.00 K  0.00 %  0.00 % httpd -k start -DSSL
29562 be/4 nobody        0.00 B      4.00 K  0.00 %  0.00 % httpd -k start -DSSL

kjournald writes 11.64 mb data and stuff. THe sum of ALL other writes are not that much. Also what is jbd2/sda3-8

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1 Answer 1

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You cannot see the real sum of all write from iotop.

  1. iotop row number is limited by your terminal height, processes maybe push off the screen by other processes with more recent I/O activities.
  2. Processes that wrote to disk then ended will not stay on the list. (eg. httpd spawn/fork process. Base on PID of httpd, I believe many of httpd child process exit already.)

Check size of httpd log files, I believe the size should show noticeable increase.

JBD2 : http://en.wikipedia.org/wiki/JBD2

Overview Quote from wikipedia:

The Journaling Block Device (JBD) provides a filesystem-independent interface for filesystem journaling. ext3, ext4 and OCFS2 are known to use JBD. OCFS2 starting from linux 2.6.28 and ext4 use a fork of JBD called JBD2

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