I was wondering what the implication are when a server PHP version is upgraded from 5.6 to 7.
My ISP manages my dedicated server, and only use PHP5.6 at the moment (will upgrade only in one month) but I need to install Magento 2.1.x now (on PHP 5.6). Can I Setup my Magento site and then later let my Host upgrade the Server to PHP 7? Is that possible? Are there any issues I should be made aware of.?
You will not have any issues with upgrading from php 5.6 to php 7 if you only run Magento 2 on that server. We upgrade our hosted clients running Magento 2 from PHP 5.6 to php 7 all the time and do not see any problems.
I agree with Anton, it should be a seamless upgrade path. Just make sure the same pecl extensions are installed, the right php 7 features are enabled for M2, and possibly ioncube support for php 7 if you use any third party extensions that require ioncube support.
Also double check OpCode caching settings to make sure those are optimized as well.
We manages our servers. We had php 5.6 running on m2 before. Upgrading to php 7.0 is harmless. But you may need to test it on your develop server first to make sure everything is fine before production server.