View Full Version : Differential vs Incremental

06-09-2011, 05:32 PM
Can someone explain the difference between these two methods of VSS backups? This is related to an Exchange 2007 VSS backup. Also, what's the 'backup transaction log' option about?


06-09-2011, 05:57 PM
Hit F1 on that screen that offers the options and you'll get a nice review.

In terms of backup transaction log, the idea is that since you're already grabbing a fully functional copy of the Exchange system, you don't really need the associated transaction log so it's an optional include. Some people really like to have it for various reasons though, so thus the ability to add it.

As to differential versus incremental. I'll just give my 15 second overview. Differential backs up everything changed since the last full. Incremental only backs up the changes since the last backup. Thus incremental is generally faster to backup, but slower to re-create the file when needed depending on how many incrementals are needed for the reconstruction. Differential takes longer the more data that's been added since the full, but theoretically restores quicker.

In the case of Asigra, I think they just added the differential option in case your database recovery mode isn't full or bulk_logged, as a workaround for those in other modes.