Which is the best method to handle incremental backup??

Few days back I was handling a support call for using Backup exec with our Idealstor appliance. The end user was having problems using Archive bit for Incremental backups because of another application clearing the bit.

We know that backup administrators always prefer a solution that will shorten their backup window. And Incremental backup, which copies all the files that have changed since last backup, is one way to speed up the process, though it takes longer to restore. Now for an incremental backup, any backup software has to first determine which files have changed since the previous backup.
Most of the leading Data Protection softwares use Archive bit, which is a flag associated with every Windows file. It is set to 1 when a file is created or modified and the backup software, after backing up the file clears the bit and sets it to 0. Next time when you run the incremental backup, the software locates the files changed or created based on the archive bit set to 1. But what if another software also clears the archive bit?? You could end up not backing up a few files:( .

Ibac Data Protection software uses Modified Date/Time/Size and byte level compare. Modified D/T/S compare is really fast when compared to other methods. IBac clocks around 3GB/min for a compare job. But again the disadvantage here is if the timestamp doesn’t change for certain files even though they are modified. Byte level compare is slower than the others but reliable especially for database backups.

Now the big question here is the best method for compare, whether it is Archive Bit or Modified Date/Time/Size or byte level?? May be the best method depends on your environment…