Upgrade Strategy for switching from Magento 1.x to 2.x
I'm running Magento 22.214.171.124 CE on a system with PHP 5.4.45, Apache 2.2.31, MySQL 5.6.41. My target is to upgrade to some version of Magento 2 residing as a new installation at a different directory but on the same server, so as to smoothly switch to Magento 2, instead of starting the upgrade on a separate server. I have a multi-domain Magento store with SSL certificate per domain, so using a new server for Magento 2 will make the transition harder and risky for going live.
If I understood correctly Magento 2.0 can indeed run on a system with PHP 5.5.x, Apache 2.2.31, MySQL 5.6.41. However, the latest Magento 2.0 CE version is 2.0.18 which has been already out of support since March 2018. So, after this upgrade, I will probably have to upgrade my server to PHP 7.0, and following go for a new Magento upgrade to the current supported version 2.2 CE.
As a result, I have the following two questions:
Is it safe for Magento 126.96.36.199 CE to upgrade PHP at some version between 5.5.22 - 5.5.x, so as to accommodate Magento 2.0.18 CE on the same server?
When I'm up to upgrade from Magento 2.0 to 2.2 CE, will I have to follow the same process; i.e. install Magento 2.2 on a different directory and proceed with new round of Configuration and Data Migration, or the upgrade process is more straightforward and smoother (something like a command-line script)?
Of course, when I install Magento 2.0.18 CE, I will make sure that my 3rd party extensions will work on both Magento 2.0.18 and 2.2 CE versions.