nagios server inside vmware

[Steve Shipway]

Mels Said:
> Cook, Garry wrote:
> > IIRC, the solution given in that thread was 'Don't use VMware'.
> >
> > I run three different Ubuntu servers (Nagios, MRTG, and NeDi) on
VMware,
> >and have no issues whatsoever with time (or anything else). 
...
> I have Suse 10.2 and Nagios, MRTG, Netdirector in production running
on
> vmware GSX server, soon we migrate it to the vmware ESX cluster. 
...
> Conclusion: why not use VMware

We tried Nagios under VMWare, and although it works, there are a number
of significant pitfalls that made us decide against it.

Most of them come down to the inaccuracy of calculating rates when in a
VM on a moderately loaded ESX server, due to the clock tick being
irregular.  

Although NTP will keep your clock in synch at an hours-minutes level,
when you get down to a seconds level it will have some seconds
apparently longer than others.  This is not a problem in many cases, but
it IS a problem if you're calculating rates by taking a sample, waiting
10 seconds (or 30 seconds, or whatever), taking another sample, and
dividing the difference by the time interval.  The shorter your sample
interval, the more that VMWare can affect things.  This is a known issue
to VMWare and they advise against running this sort of monitoring (I'm
afraid I cant find the reference, it was buried deep in documentation I
read for the v2 of VMWare).

The other issue is that, since Nagios is your central alerting system,
it is good practice to keep it as independent of other hardware and
infrastructure as possible.  This means avoiding using virtualisation
(we don't even use the SAN, let alone VMWare).  Fewer dependencies means
less change that something can knock out your monitoring system.

So, the conclusion we came to is that you can use vmware, but if you
care about accuracy in per-second rate calculations (which you may well
care about if you're thresholding on them), then don't.

Steve

-------------------------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems?  Stop.
Now Search log events and configuration files using AJAX and a browser.
Download your FREE copy of Splunk now >>  http://get.splunk.com/
_______________________________________________
Nagios-users mailing list
Nagios-users at lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/nagios-users
::: Please include Nagios version, plugin version (-v) and OS when reporting any issue. 
::: Messages without supporting info will risk being sent to /dev/null