Offsite backup products break down into 2 types, those that use partial file transfers, also known as delta blocking and those that do not; so what is the difference? Partial File transfers identify the changes in files at a very low level. After the initial full backup of a file, it is not necessary to back up the entire file, just the changes. This has the advantage of much smaller backups each evening.

Partial File Transfer; a False Economy

At a glance this seems like a good idea, but closer examination reveals the space and time benefits of partial file transfer introduce considerable disadvantages. For example, as time goes on the number of incremental slices linked to the original file increase and the process will progressively use more server centre space. Multiply this condition over the tens of thousands of files that are stored on a customer’s servers and you can see the false economy of this type of system.

Problems with File Restoration

The second, and perhaps more significant drawback, is the time needed to restore from partial file transfer systems. The recovery process does not just involve the recovery of the file itself. Instead the restoration process starts by retrieving the original file then continues by retrieving and confirming every change made to that file for the life of the backup. The longer the backup account has been active, the longer the recovery time required. Magnified over the full data store this will impact the recovery time considerably.

DataFort’s Common Sense Alternative