We have a Synthetic backup routing in place where be we seed remote office data with a single Full backup, followed by a months worth of incrementals before finally merging this into a Synthetic Full.
For the most part this routine works well however, occassionally we see an incremental stage effectively reseed all the data. As an example, we recently did a Full backup of 900Gb, followed by a couple if small incrementals but for some reason the 4th incremental was 897gb. I can assure you that very little changed on this disk and so unsure as to why backup exec was unable to determine what have already been backup up.
These kind of full re-runs can cause havoc on the network and so any insight would be invaluable.
are your incrementals based on modified time or archive bit?
Most times I've seen things like this is because of the archive bit getting reset by an AV scan or other utilities. How often is this occuring?