Multi instance question

Question

Hi thereI’m wondering if someone might be able to help with a query I have regarding instance installations. The development agency I have been working for have used ColdFusion for around 10 years and in the last 3 years, started to use a multi instances scenario for their hosting.Each CF (Coldfusion 9 Enterprise) server we have holds and runs multiple sites. These sites range from 250,000+ hits per month sites to some small 10,000 hits per month sites. Our largest server, which my question is regarding, currently has around 70 sites. This server is a virtual windows 2008 datacentre box, with 4 virtual CPU’s and 14GB of RAM. I have currently set this server to have 3 instances in a single cluster, with a sticky session and round robin setup. Each instance, plus cfusion and admin instances, is running from the same jvm.config with the following args (through trial and error):java.args=-Xmx1540M -Xms512m -server -Dsun.io.useCanonCaches=false -XX:PermSize=512m -XX:MaxPermSize=1024m -Dsun.rmi.dgc.client.gcInterval=300000 -Dsun.rmi.dgc.server.gcInterval=300000 -Dcoldfusion.fckupload=true -Dcoldfusion.sessioncookie.httponly=true -XX:+UseParallelGC -Xbatch -Dcoldfusion.rootDir={application.home}/ -Djava.security.policy={application.home}/servers/cfusion/cfusion-ear/cfusion-war/WEB-INF/cfusion/lib/coldfusion.policy -Djava.security.auth.policy={application.home}/servers/cfusion/cfusion-ear/cfusion-war/WEB-INF/cfusion/lib/neo_jaas.policyThis single cluster handles every single request to this server through IIS and does so pretty well (monitored via Fusionreactor). Ok, so that’s the background, my question is with this amount of sites and thus requests, would it be advisable to have this sort of setup with only a few instances but with each instance having lots of memory? Or would it be more beneficial to have lots of instances … maybe even one per site  / application but with a much smaller memory allocation through the JVM?Thank you so much and any help on this, would be gratefully received. Many, many thanks and kindest regardsTom Jenkins

Charlie Arehart · Answer

Tom, there’s simply no “right answer” to that. As you have expressed, proper configuration comes from trial and error. No one can look at any of the info you’ve shared and propose what “should work”. There are far too many variables (with respect to what your requests do, what else they talk to outside of CF, what kind of traffic you get—not just volume, but nature, as in if it’s a lot of spider/bot traffic, which acts differently than normal users do, for a number of reasons.)

It’s really too much to speculate, though I do realize some may try. I help people with this very sort of CF server troubleshooting each day as an independent consultant, helping dozens of shops each week, so I feel quite confident in my assertion.

I will note that I have a resource I’ve created, CF911.com, which has resources from myself and many others related to CF server troubleshooting. There you will find sections on memory configuration and troubleshooting, multiserver configuration, clustering, and more. If you prefer to dig around on your own, that should be a great starting point.

But sometimes it’s more expedient (and time-efficient) to have someone help you by direct assistance (remote shared desktop, over the web, where they can “look over your shoulder” while helping). I do this sort of help, as do others, which I list in a category of another site of mine, CF411, with tools and resources for CFers, specifically the category cf411.com/cfconsult.

I know none of this is the direct answer you sought, but I hope it’s helpful.

/charlie

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