One thing that always worries me when people talk about backing up onto an external hard drive which sits at home (usually on the desk next to the computer):
What happens if the back-up drive is lost in the same event that takes out the main computer? (E.g. both are destroyed in a fire, or stolen in a break-in.)
I'll let you decide for yourself whether you trust the various free / low-cost Cloud storage services, but my strategy is that I use Google Drive and DropBox as my "working" folders for any important data, including family photographs, legal documents, etc. I then back up my main computer's hard drive (including my Google Drive / DropBox folders) onto a portable back-up drive.
Advantages for me:
- Both my Google and DropBox accounts are free. I have access to other free Cloud storage services as well (e.g. Microsoft, Norton, etc), but two is enough for my daily needs. Having two "live" Cloud accounts gives me redundancy, and would makes it easy for me to drop one and migrate fully to the other if either is compromised, or wants to change the Ts & Cs to something that I consider to be unreasonable, or start charging me a monthly fee.
- All of my data is available on all of my devices, whenever / wherever I want to access it. I can even access it from a colleague's or friend's computer, or a public computer (such as an internet cafe or public library).
- If my back-up drive is damaged or lost, all my data is in "the Cloud".
- Even if my Google / DropBox accounts ever got hacked, I have my own back-up drive.
I'm not too worried about hackers getting access to copies of my family photos etc, but you obviously need to be careful about how and where you store any information that could be used for "identity theft", access to credit card accounts, etc.