Dell NetWorker 19.9 Administration Guide

About partial save sets

The backup sequence of partial save sets is not the same as the backup sequence for complete backups. Each partial save set provides protection for part of the file system, but the completeness and consistency of the coverage of the whole file system cannot be guaranteed.

The checkpoint restart window is user-defined and can be large. If restarted hours apart, the partial backups might provide an image of the file system that is different from the state of the file system at any fixed point in time. The resulting file system backup is not guaranteed to be consistent.

NetWorker performs file and directory backups in alphabetical order. If a failure occurs, and you restart the backup, the backup operation starts alphabetically with the next file or folder that was not previously backed up. NetWorker does not review files or folder that were previously backed up for changes. If a previously backed up file or folder was edited or added after the backup failure, NetWorker does not back up the file or directory again.

Consider the following example in which a backup is interrupted while it is saving a directory and is restarted after the directory contents have changed:

1. A save set contains /disk1/dir with files file_a, file_c and file_d.

2. The backup of the save set is interrupted while file_d is backed up.

   As a result, the first partial save set includes only file_a and file_c.

3. A user adds file_b to the file system.

4. The checkpoint restart is initiated for the save set.

   The second partial save set contains file_d and /disk1/dir, which includes file_a, file_b, file_c and file_d. However, file_b is not in the save set.