On Thu, Mar 27, 2008 at 1:52 PM, RPN01 <[EMAIL PROTECTED]> wrote: > Then to the actual question: The appliance mode works well, if you never > plan to upgrade it, or it is a stand-alone application unto itself, with > little outside information applied or kept. When the time comes to upgrade, > you have to figure out what to take from the old system, and what you don't > want to take for fear of overwriting something new and important in the new > system.
I fully agree that bundling the operating system with the application (as the VMware appliance does) is only good for disposable servers where you don't build data. I use them to kick the tires of a Wiki or some other application. In theory you should be able to take the application data out again and import that into a newer version of the appliance. Back when I was still wearing a systems management hat, we worked on application cloning. Basically when you need a server you get the current operating system image overlaid with the application payload. This avoids the need for N new appliance images each time the operating system is upgraded. With Linux on z/VM it is very easy to bring down the server and inspect the contents of its disks by mounting them elsewhere. When you have kept track of the operating system you put there, you can also tell what has been changed since then. This gives mechanical means to extract the changes and reapply them. Some schools of change management require a full set of development- test- and integration servers for each application. When there is not much change, this gets hard to justify. An installation I worked with wanted a scheme where you would "peel" the application from the server and archive that. The server would then be removed. When the server was needed again, the application "peeling" was re-applied to a fresh current empty server (looking very similar to the production systems that had been running all the time and had operating system fixes applied over time). When you can separate operating system, application layer and application data by nature (with COW file systems) the scheme gets very neat. It also saves you on disk resources and backup requirements. Rob -- Rob van der Heij Velocity Software GmbH http://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
