you have to demonstrate, that all the requirements for each OTS system are met despite the OS
Well, how do you get that demonstrated? Theoretically, on paper? Not sure that will be well perceived by an auditor…
I would recommend to Gabi to perform some testing. Based on the initial risk assessment, you should select tests pertaining to the most critical functions from the original OQ test plan.That selected set of tests will be considered as “regression tests” and should be executed after OS migration in order to demonstrate the OS change has no adverse impact / regressive effect on your system. Also some sort of IQ should be carried out upfront to document the change of OS and check basic IT fincutinalities are still OK. Hope this will help, best regards.