What is the preferred way of upgrading to new major version of Plone?

I am currently running a plone 4.0.x instance I would like to keep up to date. Buildout upgrades of minor versions like 4.0.0 -> 4.0.1 are easily done by just changing the "extends" statement in the buildout.cfg. But how about major version changes like 4.0 -> 4.1 or possibly 4.0 -> 4.2?

What is the preferred way of performing such an upgrade? Is it feasible to just point buildout.cfg to the new version (e. g. 4.2) and run buildout? Or should I rerun the quickinstaller, copy the dat开发者_如何学JAVAa.fs etc...? The latter seems to be a large undertaking, is there an easier way?

It is the same procedure. With a major version upgrade there is always the chance that some things have changed a bit that require a different approach. This is not the case for 4.1. But for version specific information please see http://plone.org/documentation/migration

Of course always create a backup of your data (Data.fs and var/blobstorage usually). And it is recommended to try the migration first on a copy of the site. General upgrade advice is in that same link.