Strange performance problems with I/O subsystem

[Ivan Voras]

On 08/03/2013 08:07, Гуляев Гоша wrote:
>    05.03.2013, 23:14, "Ivan Voras" <ivoras at freebsd.org>:
> 
>      On 27/02/2013 05:39, Гуляев Гоша wrote:
> 
>      And when I have some intensive I/O tasks (csup -g /root/mysupfile,
>      or
>      portsnap fetch update, or rm -rf /usr/obj, when system working
>      sequentialy with many files in general) my system begins
>      periodically
>      freezes. If I see gstat it shows me 100% I\O on disk.
> 
>      It usually means some kind of incompatibility of your disk drive and
>      the
>      system, its controller or its driver.
>      Sometimes it could me that the disk is broken.
> 
>    Ivan, thank for answer! I think there is no any hardware problem,
>    because as I say before, in other OS'es all works fine, without
>    performance problems. How I can diagnose problem deeply, and maybe give
>    some useful information for resolving that issue?

It is hard to give good general advice in this case.

You could maybe see if there are any error messages in your
/var/log/messages file. You could also monitor the wchan of the hung
process and verify if it's stuck in the "wdrain" state (in "top"). Maybe
you could see if there is a problem with interrupts on the machine
(either by using "systat -vm" or "vmstat -i"). You could run "iostat -x"
and see if the %busy column is 100% while there are many queued requests.

If you install smartmontools, you can run a couple of tests just in case
(try smartctl /dev/ada0 and smartctl -t long /dev/ada0).

... but if the problem is an incompatibility with the driver, all this
will probably not help you much.

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