Nothing within Article 17 talks about backups, offsite storage, readable secondaries, log shipping, or any of that stuff. In fact, there’s nothing technical there at all. No help to tell you what to do about this question.
Now, each article has expansions that further detail the information within the article called recitals. In the case of the right to be forgotten, there are two, Recital 55 and Recital 66. Recital 55 has nothing for us, at all. Recital 66 does talk about the fact that, because we’re dealing in an online world, the best available technical means should be used to deal with the fact that a person’s data may be in more than one location and we’ll need to clean that up.
And that’s it.
In fact, you can search the GDPR and not find the word, backup.
Read on for Grant’s thoughts, including what he argues is a defensible position (though we won’t know for sure until the bureaucracy runs its course).