Thanks for the suggestion. I will start monitoring the harddisk usage
and see what happens.

Thanks again,
Chris Stackpole

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Ben
Hartshorne
Sent: Friday, May 19, 2006 4:15 PM
To: [email protected]
Subject: Re: [Ganglia-general] Ganglia blackouts


Chris,

I saw this behavior when the disk I was using was too heavily used.
gmond just dropped stuff (i.e. it never got to write it into the RRDs),
and the effect was hosts that were marked down and blanks in the graphs.

The host I was using for monitoring 100ish servers was also doing very
disk-heavy DB crunching.  

-ben

On Thu, May 18, 2006 at 12:02:14PM -0500, Stackpole, Chris wrote:
> Good day everyone,
> 
> I have been noticing a odd problem with ganglia that I hope someone
can help with. I was unable to find anything in the mailing list.
> 
> The short of it is that ganglia will randomly report all the nodes as
dead, yet it will still show that it is updating the heartbeats.
> (link to imageshack for screenshot)
> http://img231.imageshack.us/img231/2910/snapshot18si.jpg
> 
> This results in my graphs having gaps.
> http://img231.imageshack.us/img231/3770/snapshot26sh.jpg
> 
> While random, this will happen several times a day. Sometimes the gap
is so small that it will not show on the day view, sometimes it will be
upwards of ten minutes. Occasionally I will get the error message
(usually a few days in between that I notice) :
> 
> Warning: arsort() expects parameters 1 to be array, null given in
/var/www/html/ganglia/cluster_view.php on line 95
> 
> which is this line in the code
> switch ($sort)
> {
>       case "descending":
> ->            arsort($sorted_hosts);
>               break;
>       case "by hostname":
>               ksort($sorted_hosts);
>               break;
>       default:
>       case "ascending":
>               asort($sorted_hosts);
>               break;
> }
> 
> Now for the part that really confuses me. I have a second system
monitoring other computers; same ganglia version and gmond (3.0.3 ). I
have set both of them up so that they will also monitor the other group.
Group A has these gaps on its nodes, but will not have them when viewing
group B. Group B monitor does not have the gaps at all.
> 
> If it was one group of systems, I would look at the systems. If one of
the monitors was doing it to both groups, I would look at the monitor as
the problem. But it is just one monitor with one group and I have no
idea what's going on.
> 
> I have already tried boosting ganglia's priority, and making certain
the two groups were on different ports just in case there was a
cpu/network flood causing it. To me, if it is still able to update the
heartbeat then it "sees" the other systems. Why then report them as
dead? (which is why, I assume, the graphs have gaps)
> 
> I would appreciate any comments and suggestions.
> Thanks everyone,
> Chris Stackpole
> 
> 
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-- 
Ben Hartshorne
email: [EMAIL PROTECTED]
http://ben.hartshorne.net

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