Snapshots sound like the ‘be all and end all’ for covering yourself from some sort of data disaster but it is an overused term. Snapshots typically have to reside on the same storage as the original data. This means that if you are using expensive 15k RPM drives for the actual data you are also using expensive drives to store what amounts to a backup of that data. The snapshot is not updated and still references the static read-only blocks, allowing you to view that data at a point in time.”]
Source: https://www.darkreading.com/database-security/the-problem-with-snapshots