Recently my employer was acquired by a bigger company and the new CTO wants us to move to their software stack. We have MySQL as the DB server, and they have Percona. So... what are the option to do it with minor downtime ?
Are the MySQL binary logs compatible with Percona ? Because if not, and I guess they aren't (at least I didn't find anything on this), then I see no suitable migration scenario for a database of 300 gigs.
Accoing to https://www.percona.com/software/mysql-database/percona-server/faq
Default scenario is mysqldump --master-data. It will cause a downtime and duration depends on your mysql server performance, tables engine and some other factors.
If you can't afford a downtime you may try pt-table-sync https://www.percona.com/doc/percona-toolkit/LATEST/pt-table-sync.html
Disclosure: I work for Percona. I'd prefer to comment but I don't have enough points on server fault.
You might find this discussion about compatibility on the Percona blog of interest https://www.percona.com/blog/2013/10/04/the-benefits-of-a-drop-in-compatible-mysql-alternative/
and also possibly this one might have information you can use in your research
https://www.percona.com/blog/2014/09/19/mysql-upgrade-best-practices/
It's open source software, and there is a free forum where you may well find answers to specific questions that might arise as you progress. Our tech team quite often provide answers on these channels too.