ganglia gmond/gmetric guide?

[der.hans]

Am 30. Mär, 2010 schwätzte Alex Dean so:

moin moin Alex,

what you wrote below is the best ganglia guide I've found. By far the best
I've found! Danke!

> On Mar 29, 2010, at 9:42 PM, der.hans wrote:
>
>> moin moin,
>> 
>> I'm using ganglia for something. Someone else set it up, but I need to add
>> a bunch of metrics ( that will then be alerted via nagios ).
>> 
>> Just using gmetric as is given in multiple examples isn't working.
>> 
>> gmetric --name distribution_release --value $( lsb_release -d | sed -re
>> 's/Description:[[:space:]]*//' ) --type 'string'
>> 
>> Running that via sudo also doesn't show up in the ganglia display.
>
> Try tracing your metric from gmond to gmetad to the web.  The path it takes 
> will vary depending on whether you use multicast or unicast, of course.
>
> After you run the gmetric command, wait a few seconds and run 'telnet 
> localhost 8649'.  gmond will give you an XML representation of all the 
> metrics it knows about.  You should see your new metric there.

We're on different ports, but I'm working it out.

We have different ports for different clusters/groupings. Some boxen
appear to be in multiple groups.

> On the node running gmetad, you can run 'telnet localhost 8651' to get data 
> for the entire cluster.  Again, your metric should be there, assuming you've 
> waited long enough for gmetad to poll gmond for new data.
>
> gmetad also provides an 'interactive' port, which by default is 8652.  You 
> can send it a query string (which sorta looks like xpath, but isn't) and get 
> the values just for a single host (or a single metric on a single host). 
> This is a good path to ganglia/nagios integration.
>
> $ telnet localhost 8652
> Connected to localhost.
> Escape character is '^]'.
> /cluster_name/host_name/load_five/
>
> ... this will return just the load_five metric on host_name in the cluster 
> cluster_name.
>
> If you find your metric in gmond, and in gmetad, then it sounds like you 
> might have a permissions problem with the rrd files.  But I seem to recall 
> those kinds of problems *do* show up in /var/log/messages.

I'm certain we do have that problem.

>> Both give exit status of 0.
>> 
>> It's not showing up in /var/ganglia/rrds.
>> 
>> Who should own those rrds files? We have them owned by root, but gmond
>> runs as an unprivileged user?
>
> They need to be writable by the user running gmetad (nobody?), and readable 
> by the Apache user.

Does ganglia automagically create the rrd files? User running gmetad needs
write perms for the rrd dir?

Thanks for the info!

ciao,

der.hans
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