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Re: What's that utility to monitor disk i/o again?



On Sun, Dec 20, 2009 at 10:01 AM, Michael Cronenworth <mike cchtml com> wrote:
> On 12/19/2009 05:54 PM, Marcel Rieux wrote:
>>
>> On Sat, Dec 19, 2009 at 6:37 PM, Marcel Rieux<m z rieux gmail com>  wrote:
>>
>>>
>>> I installed it about 2 days ago but it seems the upgrade to F12
>>> destroyed the yum.log without making any back-up.
>>>
>>
>> BTW, I'm not talking about iotop.
>>
>
> blktrace?

Yes.

> # yum install blktrace
> # mount a /sys/kernel/debug -t debugfs
> # btrace


I see no allusion to:

 mount a /sys/kernel/debug -t debugfs

in the man page. What is it for?

OTOH, without it:

btrace /dev/sda
Invalid debug path /sys/kernel/debug: 0/Success

All references at Google's, only 9 of them, say "mount a". How come
it's not "mount -a"

Here's another suggestion:

Mounting the debugfs file system

blktrace utilizes files under the debug file system, and thus must
have the mount point set up - mounted on the directory
/sys/kernel/debug. To do this one may do either of the following:

   1. Manually mount after each boot:

      % mount -t debugfs debugfs /sys/kernel/debug

   2. Add an entry into /etc/fstab, and have it done automatically at
each boot1:

      debug /sys/kernel/debug debugfs default 0 0

http://www.cse.unsw.edu.au/~aaronc/iosched/doc/blktrace.html

Why isn't this line always in /etc/fstab? Is there any security risk?

And, err... in the end, if one's purpose is only to monitor a disk
i/o, isn't iotop as good a solution?

Excuse all the questions. I'm trying to learn more about your suggestion.


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