My suggestion will be to refer the corresponding migration guide for your product to get all the details.
Please refer the below link for migration guides for different 6.3 products.
But if you have not done migration till now, my suggestion will be to directly move to 7.1 version which is having advanced features. Within 7.1 itself, if you are using Talend Cloud version, you do not have to worry about the setting up of scheduler server, log server etc as everything will be automatically handled by Talend for you.
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Part 2 of a series on Context Variables
Learn how to do cool things with Context Variables
Find out how to migrate from one database to another using the Dynamic schema