Three Copies

321 Backup – What is meant by 3 independent copies?

 

This concept assumes the first copy is the original production data but treat 2 extra copies as a minimum.

  • Independent means they have no common failure causes
  • How critical is the data and how long do you want to keep it for?
  • No media is perfect, USB sticks are notoriously unreliable

What the 3-2-1 doesn’t dictate is how many historical copies (days, weeks, months, years) of data to keep within each backup location.

Versioning is also a consideration whilst you are working on a document, to keep different copies during the drafting process during the day to go back to if you erase or change something and want to return to it.  Backups usually only happen at the end of the day/overnight.