How secure is the data and photos on an external HDD?

I back up my data and photos from my notebook to an external hard drive every 6 months. Is that enough? It would be a shame to lose all my photos + documents + data from the past 30 years.

Every 6 months is definitely enough. Your data on an external HDD is safe in any case, since no one else has access to the HDD or your data. If you are really worried about your data or data loss, you can also back it up on a cloud!

In my opinion, that's not enough. Hard drives are comparatively vulnerable and not suitable for backup. I would therefore drive at least two tracks. So instead: a backup on the hard drive, e.g. In the cloud (encrypted, e.g. With the Arq Backup software) or a backup on the hard drive, one on M-Disc and those outside your home e.g. Store with parents.

I personally prefer the hard drive + cloud solution. So I'm not dependent on always thinking about doing the backup. I use Amazon Glacier as storage and pay 2.30 euro per month for the approx. 1 TB storage that the family photos and videos take.

So there's a basic rule that data can be stamped as safe and that is the 3-2-1 rule for backups
- 3 copies of the data
- 2 media types (CD, DVD, HDD, SSD, magnetic tape or tape, cloud)
- 1 x offsite (with friends & family or cloud)

Therefore, for your photos / documents you should have at least a second external HDD if the other becomes defective so the data is not lost.

Offsite backup should also be considered if your own house burns down, since many can't simply store the data with someone else. The cloud is quite suitable for this (e.g. https://www.backblaze.com).

Feel free to comment if you have any criticism or questions.