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

[Haas, Neal]

Jumping in on the thread, what is your CDR retention set to? Do you redirect to a 3rd party CDR such as ISI? We have only a 30 day retention on our servers I believe. We never use the CDR from the server.

We had a lot of IO when our CDR was set to a few months, The IO was from the deletion of the old CDR at the end of the month. It has been a few years since we changed the settings.


Neal Haas

From: cisco-voip-bounces at puck.nether.net [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Erick Wellnitz
Sent: Friday, April 05, 2013 8:21 AM
To: Tom Piscitell (tpiscite)
Cc: cisco-voip
Subject: Re: [cisco-voip] high I/O Wait on one core

caroninit seems to be the biggest offender (by about 50x) in both disk writes and cpu usage.  Am I correct in assuming this has something to do with call detail records?

On Fri, Apr 5, 2013 at 9:02 AM, Tom Piscitell (tpiscite) <tpiscite at cisco.com<mailto:tpiscite at cisco.com>> wrote:
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<mailto: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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