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Monday, 18 May 2015 00:00

I/O tracing in Linux

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The blktrace utility (found in the Ubuntu and Debian repositories) allows monitoring what exactly data is transferred to the specified block device.

For example, you can see the general statistics and details of data exchange with /dev/sda by executing the command:

   blktrace -d /dev/sda -o - | blkparse -i - 

where blkparse is a filter for the result visualization.

If you are receiving errors about missing of /sys/kernel/debug, make sure that debugfs is mounted:

mount -t debugfs debugfs /sys/kernel/debug

You can alternatively use /proc/sys/vm/block_dump,

when writing 1 in this file the data capturing begins; when writing 0 the results are withdrawn to the dmesg buffer.

The script for simplicity of the data parsing can be downloaded here:

http://www.digitalprognosis.com/opensource/scripts/top-disk-users

The I/O monitoring not on behalf of a scheduler, but of exhaustive processes is conveniently carried out by using the iotop utility (http://guichaz.free.fr/iotop/)

Last modified on Monday, 18 May 2015 19:22
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