I'm guessing that you're asking about the Change Journal.
"Use native Filesystem Change Log Provider if available.
If this option is selected, the enhanced or conventional incremental backup will be performed using the Windows NTFS Change Log Provider if it is available. In such a case, a Windows Change Journal will be used to generate a list of files that have been modified since the last full backup and a file tree walk will not be performed"
I have tried using this in the past but found that for large file systems the management of the journal was far too cumbersome and I preferred to use the Data Protector in-build log. Unfortunately, this creates thousands of very small files in the install directory of the DP client. Because of the default block size of NTFS (4K) this caused a small DP log to take a large amount of disk space, ie 200MB of log files took up ~1.5GB of disk. So the best idea is to install the DP client on a disk with sufficient space (not C:).