That process also allows an older version of a file to be reconstructed, using a base file with any intermediate changes patched on top to reach the version you want. These piecemeal updates are also typically compressed to make the upload even faster.

Deleted files may be deleted immediately from the backup set, or retained as part of stored older versions forever or for a certain number of days. Most software lets you choose how this is handled.

Every service has its own limitations regarding how it finds, packages, encrypts, compresses, uploads, and receives changed files, which can reduce bandwidth below your maximum upstream rate. In testing with each services on a cable Internet connection that regularly tops 5 Mbps upstream, each service was able to store several gigabytes overnight.

Even if you have a 10 to 20 Mbps upstream connection, if your entire backup set is in the tens to hundreds of gigabytes you need to start with a strategy. Because none of the hosted services let you create multiple selection sets backed up to the same data set, you may want to follow this method.