How to determine if change journal support is useful in your NetBackup environment
Using NetBackup support for the change journal is beneficial only where the volumes are large and relatively static.
Suitable candidates for enabling NetBackup change journal support are as follows:
If the NTFS volume contains more than 1,000,000 files and folders and the number of changed objects between incremental backups is small (less than 100,000), the volume is a good candidate for enabling NetBackup change journal support.
Unsuitable candidates for enabling NetBackup change journal support are as follows:
Support for the change journal is intended to reduce scan times for incremental backups by using the information that is gathered from the change journal on a volume. Therefore, to enable NetBackup change journal support is not recommended if the file system on the volume contains relatively few files and folders. (For example, hundreds of thousands of files and folders.) The normal file system scan is suitable under such conditions.
If the total number of changes on a volume exceeds from 10% to 20% of the total objects, the volume is not a good candidate for enabling NetBackup change journal support.
Be aware that virus scanning software can interfere with the use of the change journal. Some real-time virus scanners intercept a file open for read, scan for viruses, then reset the access time. This results in the creation of a change journal entry for every scanned file.