Hi there,

Can anyone confirm my thoughts that the 'top' command only reports on 
hard disk use WITHIN the box rather than anything attached to it 
remotely (SAN or otherwise)?

Many thanks
Regards,
Hugo

On Wed, 15 Nov 2006 19:58:06 +0000, Hugo <hugo@nomorespamthanks.net> wrote:
> Hi there,
>
> Can anyone confirm my thoughts that the 'top' command only reports on 
> hard disk use WITHIN the box rather than anything attached to it 
> remotely (SAN or otherwise)?

top only shows CPU and memory use.

Something like iostat -x 5 will show disk (and NFS) activity).

A bientot
Paul
-- 
Paul Floyd                 http://paulf.free.fr (for what it's worth)
Surgery: ennobled Gerald.

Paul Floyd wrote:
> On Wed, 15 Nov 2006 19:58:06 +0000, Hugo <hugo@nomorespamthanks.net> wrote:
>> Hi there,
>>
>> Can anyone confirm my thoughts that the 'top' command only reports on 
>> hard disk use WITHIN the box rather than anything attached to it 
>> remotely (SAN or otherwise)?
> 
> top only shows CPU and memory use.
> 
> Something like iostat -x 5 will show disk (and NFS) activity).

What does the "IO Wait:" stand for in top's display? - I always thought 
it was how many processes were "waiting" because of Disk Input/Output 
activity?

Thanks again,
Hugo

Hugo <hugo@nomorespamthanks.net> wrote:
> What does the "IO Wait:" stand for in top's display? - I always thought 
> it was how many processes were "waiting" because of Disk Input/Output 
> activity?

No, it's a CPU figure.  It has nothing to do with # of processes.  One
process (thread actually) doing I/O can drive the iowait to nearly 100
percent *if* the machine is otherwise idle.   

The number of threads blocked on I/O is under the 'b' column in 'vmstat'
output.

Technically, the kernel maintains timestamps for when the CPU is running
user code, kernel/system code, and when the CPU is idle.  I/O wait is a
subdivision of idle time.

The figure tends to be misinterpreted.  It's not always an indication of
a problem, and it's not always present even when there is a problem.  So
in isolation, it's not appropriate as an indicator of anything.

Due to the common misinterpretation, Solaris 10 has removed the
calculation.  The value is forced to 0 and all CPU idle time is reported
strictly as 'idle'.

-- 
Darren Dunham                                           ddunham@taos.com
Senior Technical Consultant         TAOS            http://www.taos.com/
Got some Dr Pepper?                           San Francisco, CA bay area
         < This line left intentionally blank to confuse you. >

Hugo wrote:
> Hi there,
> 
> Can anyone confirm my thoughts that the 'top' command only reports on
> hard disk use WITHIN the box rather than anything attached to it
> remotely (SAN or otherwise)?
> 
> Many thanks
> Regards,
> Hugo
as others have pointed out, there are no I/O statistics in top. But you
might want to try sysstat to get an impression of what is going on in
your system.

Get it here: http://www.maier-komor.de/sysstat.html

Tom