The script is just a .bat file that uses the NET USE command to map a network drive to the share on the Celerra.  This worked fine, except I noticed that only files with read access for everyone were being backed up.  All of my user profile or home directories were returning access denied errors.  I did not want to grant everyone access to all files and directories.

To fix this I had to add a username and password to the NET USE command to map the drive as a user that has read access on all directories on the shares.

I created a backup admin user for this and set all files and directories to allow this user read access.

The pre backup script mount_x.bat now looks like this:

net use /delete X:
net use X: \\NAS\Share /USER:Domain\backupadmin password

Once the backup is complete I then run a post backup script to to remove the mapping with another script umount_x.bat:

net use /delete X:

The scripts have to be in C:\Program Files\avs\etc\scripts\ on the avamar client.