[Xymon] Monitoring a simple cluster

[White, Bruce]

I have a couple of "traditional" active/passive clusters.  For items
that need to be present on all nodes, I sue the standard monitoring
available with xymon and it's client.  For things that need to only
appear on the active node,  I handle in one of two ways. 

 

Way #1 -  I created striped down Xymon clients which runs with the
application within the cluster.  I have HP service Guard clusters, so
this is easy to do within their frame work of scripts handling most
everything.   I create a new client within the disks which migrate
within the cluster, edit the  xymonclient-<O/S>.sh script within this
new client directory structure and assign an IP/host in the hosts.cfg
which matches the IP which floats within the cluster.  I pull all the
CPU, memory, etc. stuff out of the new xymonclient.sh and focus on the
disks, procs, ports, etc. which tend to be very application specific.
I let standard Xymon take care of the rest.   

 

 

Way #2 - I setup the IP/Host which matches the floating IP under cluster
control and run scripts from the Xymon server pointing at the floating
IP.  The scripts report status to the Xymon server using the Name
associated with the floating IP, so to the outside observer it looks
like a new server, but its just an application running where it needs to
under cluster control.  

 

For check just SMTP the second might be the way to go, as you could just
use the standard Xymon SMTP test to see that SMTP is running on the IP
which floats.

 

            ......Bruce

 

 

From: xymon-bounces at xymon.com [mailto:xymon-bounces at xymon.com] On Behalf
Of Dan Smith
Sent: Thursday, June 21, 2012 12:17 PM
To: xymon at xymon.com
Subject: [Xymon] Monitoring a simple cluster

 

Red Hat 5.8 server, 5.5 clients.  Xymon 4.3.7 clients and server. 

 

I am trying to put together a quick cluster monitor using depend and
combos, but I think I'm stuck.  Has anyone else done this?

 

I have two servers: smtp01 and smtp02 that are in an active/passive
cluster.

The smtpd process only runs on the server that is active, but there are
other processes that need to be monitored on both hosts (e.g.
clurgmgrd).

 

I would like to go red and have an alert if one of the required
processes goes down on either server, but I only want an alert if the
active node of the cluster has a problem with the smtpd process.

 

My initial idea was to have procs go red for clurgmgrd and yellow on
smtpd, use NOPROPYELLOW, and then use a combo so I could see what host
was active...

 

hosts.cfg:

1.2.3.4   smtp01 # NOPROPYELLOW:procs

1.2.3.5   smtp02 # NOPROPYELLOW:procs

1.2.3.6   smtpHA # smtp

 

analysis.cfg:

HOST=smtp01

            PROC   clurgmgrd

            PROC   smtpd

HOST=smtp02

            PROC   clurgmgrd

            PROC   smtpd

 

combo.cfg:

smtpHA.procs = (smtp01.conn && smtp01.procs) || (smtp02.conn &&
smtp02.procs)

 

Unfortunately a yellow status is equal to a 1 for the combo, so even if
both sides of the cluster were down, the combo would still show as up
(green&&yellow is 1&&1).

 

Then I thought I could cover the scenario by making a "depends" test,
but depends seems to be focused on disabling tests if another status is
red...which doesn't work either since I don't want the page to go red.

 

This isn't a huge issue because the smtp poll on smtpHA will trigger red
if both nodes are down, but it seems like there should be an easy way to
do this.

 

Am I making it more complicated than it needs to be, or am I better
writing a custom monitor?

 

Thanks!

 

-dan


 
Bruce White
Senior Enterprise Systems Engineer | Phone: 1-630-671-5169 | Fax: 630-893-1648 | bewhite at fellowes.com | http://www.fellowes.com/
 
 
 
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