Differential Incremtnal Backup Missing Files

I have been working on evaluating differential incremental backups for our GroupWise post offices. In my evaluation I have found a significant time and disk space savings, but I have ran into an issue that support has been, as of now, unable to answer. Following is a summary of our environment and the issue:

NBU master server 6.5.1 running on Solaris 10u6
NBU media serer 6.5.1 running on Solaris 10u6
NBU client running on Win 2k3 with NBU 6.5.1 client

Issue:

Every day there are a few directories that do not back up all changed files. There are some consistencies between what is not backed up:

1. If any files are missed it is always only one file
2. If a file is missed it is going to have a timestamp between 6:00am and 6:12am

Files with timestamps between 3:00am and 5:59am and 6:13am on are always backed up. Most files with timestamps between 6:00am and 6:12am are backed up, even if a file was missed in this time range and there are other files that fall into that time range they will be backed up. The directories missing files are not consistent (i.e. directory1, directory2, etc.). A directory that missed a file yesterday will have no problems today, and there are no noticeable patterns in the directory names missing files.

NBU policy and schedule setup:

Checkpoints are set to every 5 minutes
Collect true image restore information w/ move detection is enabled
Allow multiple data streams is enabled

Daily incremental starts at 4:30am and generally run until about 5:50am
Daily Full starts at 7:00am
Media multiplexing is set to 5

This is an evaluation, so we are running a full backup after the incremental to ensure we are getting a good backup until we are comfortable with and confident in the incremental backup process.

NBU Storage Unit setup:

Multiplexing is enabled
Max streams per drive is set to 10
Reduce fragment size is set to 50mb

This is a virtual tape library

NBU client setup:

Archive Bit / Incrementals is set based on timestamp
Time Overlap is set to the default 60 minutes

This is set to timestamp because we are dealing with a snapshot (the archive bit would be overwritten every day)

Target Data:

The target dataset is a BCV (snapshot of live data). The snapshot is taken every day before the backup at 3:00am. The data sits on a 3PAR InServ S400.

The data is backed up at the top level as c:\dataset\*

There are 248 directories under the “dataset” directory, which cause 248 child jobs to spawn off of the main job.

NBU support has been working with me on this issue since February (yes over 5 months) and we have made considerable progress, but we are still missing a small amount of files during our incremental backup. For example today I analyzed 40 directories and found two of the directories missed a file that should have qualified for the incremental backup. Any suggestions or advise would be greatly appreciated.