This is one of the biggest problems with people hating on docker... They don't understand what it is and actually does. Great comment!
But putting pb of data in docker three years ago is just insane.
There are still things not clear right now,which are not stable ( not in unstable destroying data) but unstable in: if something goes wrong with your data you need to dig deep and find out what's going on. If stuff changes every few month. You will have a hard time.
Also, enterprise concerns like:
Will there be a docker standard from Google and Facebook? Will AUfs be Version 4 or scrapped again? Will the composer format stay? How to manage runtime upgrades? Ie syncronize 1000 dockers with one version update than another 1000 with another software. So that one update depends on another. Etc etc etc.
Three years ago it just wasn't there. Two years ago I would have said: "good enough" to play around. One year ago it started to get really interesting for enterprise.
That's why I say: you handle pb of data,with docker,three years ago?
Balls of steel.
But with that said, if you have replication and operational workflows set up, you minimize the chance of issues.
If you have mission critical data, you should set up your database to handle failovers of any type, let alone docker.