[cisco-voip] high I/O Wait on one core

[Tom Piscitell (tpiscite)]

Erick,

You can use the FIOR utility from the CLI to identify which processes are writing to the disk. 

admin:utils fior 
      utils fior disable
      utils fior enable
      utils fior list
      utils fior start
      utils fior status
      utils fior stop
      utils fior top

Here is a typical use case:

1. Enable the FIOR utility before/during a time of High IO Wait
	admin:utils fior enable
	File I/O Statistics has been enabled.
	admin:utils fior start
	Loading fiostats module: ok
	Enabling fiostats : ok
	File I/O Statistics has been started.

2. Wait a couple minutes. FIOR will poll for data every 5 seconds I believe. Then use utils fior top to see whats hitting the CPU the hardest:

admin:utils fior top ?
Syntax:
utils fior top n sort_by [start=date-time] [stop=date-time]

         n:            number of processes
         sort_by:      read, write, read-rate, write-rate
         date-time:    of the form %H:%M, %H:%M:%S
                                   %a,%H:%M, %a,%H:%M:%S
                                   %Y-%m-%d,%H:%M, %Y-%m-%d %H:%M:%S
Example:
admin:utils fior top 10 write start=2010-04-20 10:00:00 stop=2010-04-20 10:30:00

This of course won't tell you *why* a process is hitting the disk, but it will at least show you who has the most read/writes. To answer the why question you would need to look at traces for the offending process/service.

HTH,
-Tom

On Apr 4, 2013, at 5:43 PM, Erick Wellnitz <ewellnitzvoip at gmail.com> wrote:

> Hello all!
>  
> I have a dual 4 core IBM 7835I3 which is my publisher.   One one core of the first CPU the I/O Wait is through the roof.  RTMT shows that writes to the hard drives are at between 600 and 700 MB/s which is exponentially higher than the subscriber on the same model of hardware.
>  
> Short of calling TAC is there any way to figure out what is causing the extremely high volume of writes to the drives?  I already stopped most traces and looking at the processes doesn't give any clues.
>  
> Thanks again!
>  
>  
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