<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> <HTML> <HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"> <META NAME="Generator" CONTENT="MS Exchange Server version 6.5.7652.24"> <TITLE>Best way to monitor application clusters</TITLE> </HEAD> <BODY>  I've recently started using nagios in our development environment, and have knocked a few plugins for some of our programs (i.e. monitor a log on a remote server to make sure it's growing, but not growing too fast or too slow, or jumbo pings between two remote machines), which is very impressive. One thing I would like to monitor is a group of hosts/services, and flag a warning if x% are not available, and a critical if y% are offline. A common example would be checking DNS services. If you have 4 DNS servers, you don't want to be woken up at 3AM if one falls offline, but if 3 are offline you would, and if 4 are offline you want an APB. You still want to see the servers are offline though on a webpage, and possible a notification in work hours. I'm aware of host/service groups, being one way of doing it, however I'm unsure if notifications can be set based on % of hosts/services available in a group. Another way would be a "virtual host", with a custom "check_host_alive" which checks all hosts in a collection, and returns an OK/critical/warning based on the number of failures, and likewise with "virtual services". The original hosts could then be monitored separately, or even not at all. For example, a service I would like to check is whether 3 mysql databases are in sync with each other. I currently have a web page that compares the log positions. It seems to me that logically the service should run on the mysql boxes, however I only want it running on Another example would be I have a piece of java software (call it "A") that must run on at least one of 4 machines, and preferably on 2 of them. I don't care which machine it's on, but if it's not running I want to be notified in red lights. I could have a simple "virtual service A", which would critical on 0, warn on 1 and OK on 2 or more. This would be attached to "virtual host A", which would critical on 0, warn on 1 and OK on 2 or more of the servers that the service runs on. I'd also like a "simple" login to the web page which would only display the "clusters" of services/hosts, rather than the total view, which would allow our support engineers to easilly see real problems, and allow management to sleep hapilly with lots of green lights. I must admit I'm leaning to the virtual host/service thing, but I was wondering if there's a standard/better way of monitoring these kind of things? Thanks <a href="http://www.bbc.co.uk">http://www.bbc.co.uk</a> This e-mail (and any attachments) is confidential and may contain personal views which are not the views of the BBC unless specifically stated. If you have received it in error, please delete it from your system. Do not use, copy or disclose the information in any way nor act in reliance on it and notify the sender immediately. Please note that the BBC monitors e-mails sent or received. Further communication will signify your consent to this.</BODY> </HTML>