On Wed, Aug 12, 2009 at 3:39 PM, Robert J Brenneman<[email protected]> wrote:
> Generally - you use Linux HA for stuff that does not include its own > HA support in the product. You could think of it as strapping HA > capability onto the outside of an existing product. Word of caution though, and reference to the law of diminishing effects. Unlike you most x86 configurations, your Linux on z/VM installation has already invested a lot to get you a reliable platform. Ad-hoc duplication of components may not achieve anything useful, but does increase the cost in resource consumption and complexity. When the PEBKAC failures are my far the most dominant cause for an outage, then increasing complexity may not be a good thing to do. > WAS and DB2 on the other hand actually come with HA clustering support > out of the box, so Linux HA doesn't really give you anything more > above that. In some cases this support actually comes in a different box ;-) I believe with WAS it is a common configuration to combine application testing and deployment with fail-over support. The idea being that you need a hot standby anyway and can abuse that to test and deploy your application. When you're done fiddling with it, you change the roles. Such a scheme may not be the best approach in this environment. :story. Some time ago I was listening to someone selling a rather complicated framework for HA which includes automatic deployment of applications on whatever "lukewarm servers" (my words) ready to deploy an application that needed a home. These lukewarm servers were running "only" the Java-based HA framework. The customer asked what the reason was for all these in-queue idle servers eating up his resources. We were told this was because the server would be unused anyway (yeah) and it saves the Linux boot time. When the customer explained that a Linux virtual machine was typically at root prompt in 3 seconds, the presenter was pretty much done... :-) Rob -- Rob van der Heij Velocity Software http://www.velocitysoftware.com/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
