The security dimensions of Big Data are well rehearsed

The security dimensions of Big Data are well rehearsed, and protection must be a given.

I don’t understand the sentence. Could some please paraphrase it?

'Whew! If anyone ever asks for an example of bad writing, that’s it. If you know what he is saying, he doesn’t need to say it, and if you don’t, he hasn’t told you anything.

By Big Data, he means organizations that have immense amounts of data. They have policies and procedures that are supposed to keep the data private, but if you pay attention to the news, it doesn’t.

When someone says “is a given”, it usually means that it’s not to be relied upon, although the author in this (and most cases) is unaware of that fact. It’s easier to say “protection is a given” that to say “we’re doing this, this, and that, which, come to think of it, aren’t very effective,” which causes the high muck-a-mucks to get their undies in a bundle.