Netbackup Desktop and Laptop Option (DLO) may seem to lock the Outlook PST file for a long time during backup.

Article:TECH150554  |  Created: 2011-01-27  |  Updated: 2013-11-13  |  Article URL
Article Type
Technical Solution



This usually happens after a booting a desktop computer configured with Outlook and DLO Desktop Agent.
DLO attempts to scan the Outlook PST files and seems to lock it for a long time.



Microsoft Outlook may fail to start and the following error message appears:

"The set of folders could not be opened. You must connect to your Microsoft Exchange Server computer with the current profile before you can synchronize your folders with your offline folder file"


“The set of folders cannot be opened. The file <Folder_path> *.PST is in use and cannot be accessed”


This applies to DLO version 6.1 MPx
Microsoft Outlook version 200x
Desktop OS Windows XP SP2, SP3, Vista and Windows 7


The error is reported by Microsoft Outlook and is external to DLO.
Kindly refer these Microsoft KB articles before applying the fix provided below.

Error messages when you try to connect Outlook 2007 to Exchange Server: "The action cannot be completed" or "Your Microsoft Exchange Server is unavailable" or "Cannot start Microsoft Office Outlook"

You may receive an error message and Outlook does not start when you try to start Outlook on a computer that is running Windows XP

OL2002: Error Message: "Your Server Has Reported a UID Which Does Not Comply with the IMAP Standard"

Personal folder files are unsupported over a LAN or over a WAN link

Other causes:

> Check if the affected user has Outlook configured with a MAPI and/or IMAP accounts

> IMAP traffic is usually slow and takes time to download messages from the email server that is usually on the WAN.

> When a desktop computer is started, Outlook and DLO attempt to access the PST at the same time. Other applications that automatically start-up with Windows, like Google desktop search, Windows Desktop search, Office communicator, Xobni Outlook plugin etc. also attempt access the same PST for indexing purposes.

> DLO starts to scans the PST for changes and then starts a backup. Meanwhile Outlook with IMAP accounts may attempt to synchronize messages from the server over a slow LAN/WAN connection.

The combined effect of everything listed above put a freeze on the PST and prevents any of the individual applications to fully access the PST.


  1. Introduce a delay in the startup of the DLO Desktop Agent to prevent the PST from getting swarmed with too many access requests. This can be done under.. Tools --> Options --> Global Settings --> Options --> Time to delay Desktop Agent startup after user logs-in

         You may set the delay to 360 seconds (6 minutes) or greater.

  1. The delay can be further increased for older desktops / laptops that are short on resources (slower processor, less available memory, slow WAN/LAN links)
  2. Search and Indexing applications like Google desktop search, Windows Desktop search, Office communicator, Xobni Outlook plugin etc. should be configured to exclude Outlook PST files and / or fine tuned to index files as per schedule.


  1. Netbackup DLO version 6.1 MP5a and above has the feature to use "VSS backup of Outlook PST files". Kindly refer the article listed below to improve the PST backup performance when DLO is configured to use VSS backup method.

DLO backup of Outlook PST files is slow during the "Copying local" phase of the backup job

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