Our Exchange Policy limit user mailbox up to 300 MB, so users move their exceeding mail quota to local pst files. This files can grow up to 4-5 GB, but everage is aroutd 2,5-3GB. Many PST files are present. If user reduces pst dimension for any reason (by deleting or moving mail to another pst), the pst on the storage server doesn't reduce its dimension, as local pst file do. At next dlo startup, Agent start scanning the pst file to check difference between local pst file and storage pst by reading EACH mail that is stored in the local pst file (5-6000 e-mail) and adding them to the pst located on the store. This pst can grow up to 20 GB for a local pst of 2GB.
As you can immagine, this scan totally kills users computer, even if "user activity limitation flag" is active.
This problem is present only on pst above 1,6 GB.
From my experience, seems that DLO Agent can't handle correctly pst file larger than 1,6 GB (the old pst limit for Outlook XP overcamed in Outlook 2003)
All client are running Windows XP Sp2/3, Office 2003 with latest patch, Symantec BAckup Exec 12 with latest patch.
This problem was present since Veritas BAckup Exec 10.x