Permission Change = HUGE Differential!

[Homercidal]

I noticed some of my Differential backups were HUGE, only 2 days after a Full backup.  I also figured out it was because I had made some rights changes on a directory that contains about half of our backup.  Needless to say, I can't see continuing like this and running out of differential tape in 2 days.

I'm currently running a FULL backup using Modified Date and plan to run another Differential tonight to see what happens.

I don't know if I should continue using Modified Date instead of Archive bit.  I anticipate making more changes to that directory in the coming weeks as we bang out some process changes and more people need access to it. 

Is Modified Date an acceptable method, or is there another process I can use that allows me to use the Archive bit without encountering a problem along the line?

Thanks!

-Jim

[sbora]

Modified time backup method has certain advantages like :

it is fast compared to archive bit 

if full backup fails the time is not recorded in the database and next incremental/differential backs up all data

it is more accurate than archive bit since a lot of processes (e.g. some AV) can change archive bit

I am not sure if changing permission will modify the time and increase the next backup size. Are you sure there wasn't any other change on the files in the directory?