What is the Correct Thinking?

[WuMyster]

Is it right to think that having my data stored on more than one HDD is better than just one?

If I have everything on a 6TB drive and that fails, I lose everything. Whereas if I had it split on 3TBs, I'd lose half.

 

[Prophet]

Mirror your data to another drive, don't split it.

losing half of your data is still bad.

Get a NAS drive and replicate your data to that.

 

[Boogieman_WD]

Hey there WuMyster.

I second @Prophet's advice. If the data is important to you, distributing it between two or more drives does not make it safe. You'd still lose it if the worst happens and those drives or one of them fails (you'll not lose all of it but a huge portion nonetheless). So go with either a NAS or an external drive or some other backup solution, but you should have a copy of that said data, not use the NAS/external drive for storage. This is a common misconception when it comes to backups.

Hope that helps.
Boogieman_WD