CentOS6.6 + Postfixadmin 2.3rc5 + PHP5.3, upgrade to PHP5.4

Solution 1:

My go-to for PHP on CentOS is the remi repository. Remi is a Red Hat employee who also packages the official Red Hat PHP packages, in addition to his own repos where he maintains compatible packages which are more current versions. Simply installing and enabling the remi repository on CentOS 6 and then yum updating is sufficient to upgrade to PHP 5.4. (The repos ship disabled by default and you need to explicitly enable them.) You can also enable PHP 5.5 or 5.6, and probably should do so since 5.4 will be EOL soon, and almost all packages that work on 5.4 will also work on 5.5 or later.

For compatibility, I would just go ahead and upgrade Postfixadmin and PHP at the same time. You'll need a short maintenance period (five minutes or less?) or a slightly longer period if you need to do database schema changes and have a large database (you likely don't). The Postfixadmin web site says that loading upgrade.php after the upgrade is sufficient.

Remember your backups.