Have you ever heard of 3-2-1 backup rule? Let me explain it in a nutshell.
This rule is recommended by US-CERT, it is quite easy to understand and quite easy to follow. However don’t get me wrong, you need really more than this rule to get your backup done the right way.
3 copies
One copy of your data is no backup, here you have two backups which are extra copies of your data so that makes three copies in total.
2 different media types
Having two different media types reduces various kinds of risks.
1 copy offsite
One of your backups needs to be stored offsite (that is a very important point).
Is that everything you need to know?
Well I explained to you the 3-2-1 rule in a nutshell. There is far more to understand. As explained by the linked resources, various technologies have pros and cons. Have those in mind in your analysis.
More importantly, you need to have a backup strategy that includes a schedule (exact or approximate). Can your data be half corrupted in a way that requires you to go back in time? Do you need to keep a number of daily/weekly/monthly backups? How many hours of data can you afford to lose if you take the last backup? So, you get my point.
The 3-2-1 backup rule is just a baseline.
Note that backup is not always the only need, sometimes you also need an archive, which is something a little different.
Stay tuned for other articles about backup.