My answer to "[want try lampcms]how to safely upgrade php 5.1.6 to php 5.3.3 , what should be backup before"

This is my answer to a Question on Support site for LampCMS project

I would say just install php 5.3.3 and try it.

Some existing php programs may have a few errors (most likely just warnings) pop up here and there after the upgrade, those can be easily fixed.

The 5.1.6 is really an outdated version, 5.3.3 (or newer) is much more effecient and just a faster version.

You will almost certainly will want to also use the APC extension instead of eAccelerator or if you really like eAccelerator then at least upgrade it to version compatable with php 5.3. I personally would just go with APC since it's not standard part of php and is maintained by php, unlike eAccelerator.

You don't have to do anything with nginx, just upgrade php, make sure you install php-fpm and use run php as fastcgi under php-fpm management.