Normal Operation For the normal operation or installation of a Magento store, only 2 folders need to be writable: /media - for web accessible files, such as product images /var - for temporary (cache, session) and import/export files Installation During installation Magento Install Wizard will create app/etc/local.xml file which contains database configuration and global encryption key for your Magento copy. Meaning app/etc folder has to be writable to web service.