Hard disk usage is 100 Percent Busy for any command Post: 302145195

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Operating Systems AIX Hard disk usage is 100 Percent Busy for any command Post 302145195 by bakunin on Tuesday 13th of November 2007 06:22:50 AM

11-13-2007

Registered User

First off: if you tar something, the command will read something on your disk (a bunch of files) and then create an archive from it, writing that to the disk (most of times). What else then seeing activity on your disk do you suppose will happen?

Additionally i would like to clarify what the "% tm_act" field in the output of iostat means:

The OS has a sensor, regularily asking the disk if it is busy or not. When the disks aswers half of the times "I'm busy", then the "% tm_act" will be 50%. If the disk answers every time "I'm busy" then tm_act will be 100%, etc.. A disk answers with "busy", when there are requested operations not yet fulfilled, read or write. If many very small requests go to the disk the chance of the sensor asking exactly when one such operation is still open goes up - much more so than the real activity of the disk.

So, "100% busy" does not necessarily mean the disk is at the edge of its trasnfer bandwidth. It could mean either that because the disk is getting relatively few but big requests (example: stream I/O) but it could also mean that the disk is getting a lot of requests which are relatively small so that the disk is occupied most of the time, but not using its complete transfer bandwith.

To find out which is the case analyse the corresponding "Kb_read" and "Kb_wrtn" column from iostat. You know how much a modern disk drive can approximately handle (~17MB/second) physically and bypassing any cache. Compare your data to this (rule-of-thumb-)value and you will get a more detailed picture.

bakunin

Last edited by bakunin; 11-13-2007 at 08:42 AM..

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tm::coverage

TM::Coverage(3pm)					User Contributed Perl Documentation					 TM::Coverage(3pm)

NAME

       TM::Coverage - Topic Maps, Code Coverage

DESCRIPTION

       This auxiliary package keeps track of the code coverage. Probably quite irrelevant for a user.

       Automatically generated for TM (1.44).

	  ---------------------------- ------ ------ ------ ------ ------ ------ ------
	  File				 stmt	bran   cond    sub    pod   time  total
	  ---------------------------- ------ ------ ------ ------ ------ ------ ------
	  blib/lib/TM.pm		 96.4	84.5   58.0   93.7   90.6   27.5   89.6
	  blib/lib/TM/Analysis.pm	100.0	90.9	n/a  100.0  100.0    0.0   97.5
	  blib/lib/TM/AsTMa/Fact.pm	100.0	 n/a	n/a  100.0    n/a    0.0  100.0
	  blib/lib/TM/AsTMa/Fact2.pm	100.0	 n/a	n/a  100.0    n/a    0.0  100.0
	  blib/lib/TM/Bulk.pm		 76.8	71.4   62.5   85.7  100.0    0.0   75.3
	  blib/lib/TM/CTM/CParser.pm	 65.6	34.3   31.0   84.6    0.0    1.6   52.5
	  blib/lib/TM/CTM/Parser.pm	 90.9	50.0	n/a  100.0    0.0    0.0   79.4
	  blib/lib/TM/DM.pm		100.0	65.0   66.7  100.0    n/a    0.0   96.5
	  blib/lib/TM/Graph.pm		 99.1	88.5	n/a  100.0  100.0    0.0   97.4
	  blib/lib/TM/Index.pm		100.0	80.0   60.0  100.0   83.3    0.3   87.8
	  .../Index/Characteristics.pm	100.0  100.0	n/a  100.0    0.0    0.0   97.0
	  blib/lib/TM/Index/Match.pm	 98.5	87.5	n/a  100.0  100.0    0.5   97.6
	  blib/lib/TM/LTM/CParser.pm	 84.9	45.3   42.7   98.2    0.0    0.2   67.8
	  blib/lib/TM/LTM/Parser.pm	 95.7	62.5   50.0  100.0    0.0    0.0   87.1
	  blib/lib/TM/Literal.pm	 45.8	 0.0   11.8   30.0    0.0    0.4   24.2
	  blib/lib/TM/MapSphere.pm	 96.5	84.6   68.8  100.0  100.0    0.0   91.7
	  .../TM/Materialized/AsTMa.pm	100.0	 n/a	n/a  100.0    0.0    0.0   95.5
	  ...ib/TM/Materialized/LTM.pm	100.0	 n/a	n/a  100.0    0.0    0.0   95.5
	  .../TM/Materialized/MLDBM.pm	100.0	83.3	n/a  100.0    0.0    0.0   92.6
	  ...b/TM/Materialized/Null.pm	100.0	 n/a	n/a  100.0    n/a    0.0  100.0
	  ...TM/Materialized/Stream.pm	100.0  100.0  100.0  100.0    0.0    0.0   96.0
	  ...ib/TM/Materialized/XTM.pm	100.0	 n/a	n/a  100.0    0.0    0.0   96.7
	  blib/lib/TM/PSI.pm		100.0	 n/a	n/a  100.0    n/a    0.0  100.0
	  blib/lib/TM/QL.pm		 91.4	61.5   66.7  100.0   50.0    0.1   83.9
	  blib/lib/TM/QL/CParser.pm	 76.2	42.4   41.9   90.3    0.0    9.1   62.0
	  blib/lib/TM/QL/PE.pm		 83.8	77.3   80.0   91.7    0.0   52.5   80.5
	  blib/lib/TM/QL/TS.pm		 65.2	35.4   27.8   70.8   53.3    2.4   56.9
	  blib/lib/TM/ResourceAble.pm	 88.1	87.5	n/a  100.0  100.0    0.0   90.0
	  .../TM/ResourceAble/MLDBM.pm	100.0	75.0	n/a  100.0    0.0    0.0   94.2
	  blib/lib/TM/Serializable.pm	 94.9	65.6  100.0  100.0  100.0    0.0   84.1
	  .../TM/Serializable/AsTMa.pm	 99.1	87.9   66.7  100.0  100.0    0.0   94.2
	  ...TM/Serializable/Dumper.pm	100.0	 n/a	n/a  100.0    0.0    0.0   93.5
	  ...ib/TM/Serializable/LTM.pm	 94.1	 n/a	n/a   83.3  100.0    0.0   92.0
	  ...ib/TM/Serializable/XTM.pm	 96.3	85.2   72.9  100.0  100.0    0.2   91.5
	  .../lib/TM/Synchronizable.pm	100.0	75.0  100.0  100.0  100.0    0.0   97.2
	  ...M/Synchronizable/MLDBM.pm	100.0	50.0	n/a  100.0    0.0    0.0   89.3
	  ...nchronizable/MapSphere.pm	100.0	63.6   64.3  100.0  100.0    0.0   88.6
	  ...TM/Synchronizable/Null.pm	100.0	 n/a	n/a  100.0    0.0    0.0   87.5
	  blib/lib/TM/Tau.pm		100.0	91.7   80.0  100.0    0.0    0.0   95.6
	  blib/lib/TM/Tau/Federate.pm	 63.2	39.3	n/a   62.5   27.3    0.0   54.5
	  blib/lib/TM/Tau/Filter.pm	100.0	91.7   66.7  100.0   50.0    0.0   90.0
	  .../TM/Tau/Filter/Analyze.pm	100.0	 n/a	n/a  100.0  100.0    0.0  100.0
	  blib/lib/TM/Tree.pm		100.0	57.1   44.4  100.0   66.7    0.0   88.0
	  blib/lib/TM/Utils.pm		100.0	50.0	n/a  100.0    0.0    0.0   89.3
	  ...ib/TM/Utils/TreeWalker.pm	100.0  100.0	n/a  100.0    0.0    0.0   96.0
	  ...ib/TM/Workbench/Plugin.pm	100.0	 n/a	n/a  100.0    0.0    0.0   75.0
	  ...M/Workbench/Plugin/Tau.pm	 87.5	50.0	n/a   80.0    0.0    0.0   73.1
	  yapp/astma-fact.yp		 96.9	91.5   73.3   97.8    0.0    4.8   92.7
	  yapp/astma2-fact.yp		 97.4	91.6   58.3  100.0    0.0    0.2   91.6
	  Total 			 76.8	45.2   40.2   91.2   57.0  100.0   63.8
	  ---------------------------- ------ ------ ------ ------ ------ ------ ------

SEE ALSO

       TM

COPYRIGHT AND LICENSE

       Copyright 200[8] by Robert Barta, <drrho@cpan.org>

       This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.10.1							    2008-10-05							 TM::Coverage(3pm)

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