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Oops? Windows 7 Backup omits key Outlook mail files

    Question

  • I use Microsoft Outlook 2007 with the Outlook Connector to sync my Live Mail accounts.  The backup tool in Windows 7 will smartly backup the C:/Users/User/AppData/Local/Microsoft/Outlook/ folder's PST files. Yeah! Except for users like me using the Outlook connector, the meat is kept in an OST file (offline outlook cache file) while the PST file is a paltry few kilobytes of nothingness.

    Here's where it get worse.  I can specifically add the entire Outlook appdata folder to the backup set & all the other cruddy xml and obi files get backed up, EXCEPT the OST cache file!  The backup tool must be set to skip this file type.  Is there any way to back this up?

    Even the additional download pack to add the backup functionality within Outlook applies only to PST files.

    My only options I see (neither are desirable):
    - auto archive emails in a PST which will be backed up
    - install a 3rd party backup that doesn't ignore OST files

    Any help?
    Tuesday, August 11, 2009 3:53 AM

Answers

  • Thanks for taking the time to respond.  Your response was very thorough and helped me understand the reason behind why for most people backup of the OST file is not desirable.

    There is one thing I disagree with in my particular case (but not necessarily universally):

    "So, Backup the OST files is needless."

    There are two reasons why having a periodic backup of offline files, stored independendantly may be useful:
    1. the user deletes an email(s) accidentally

    2. the server deletes an email(s) in error

    In my case, Live Mail had a server error which deleted years of valuable personal emails.  The local cache was updated before I discovered the issue and there was no recourse to retrieve them.

    So, I think my solution will either to try to hack the backup tool to include OST files or just periodically save a copy of the cache myself manually.

    I think I learned an important lesson on taking the cloud for granted.
    • Proposed as answer by Brian Borg Friday, August 14, 2009 1:26 AM
    • Marked as answer by Dale QiaoModerator Wednesday, August 19, 2009 1:42 AM
    Thursday, August 13, 2009 5:38 PM
  • Hello customer,

     

    By default, the .ost file is related to Exchange Server and is associated with a mailbox on the Exchange server. I would like you to know Microsoft does not offer the solution to open the orphan OST file due the security issues. To keep the OST secure, Exchange and Outlook store a key derived from the mailbox's unique entry ID as part of the user's profile. If the user's profile doesn't point to that particular mailbox, the user can't unlock the OST. There is no method to open the standalone OST file directly in Outlook since it is encrypted with the Exchange server mailbox. You need to connect the OST file to the original Exchange mailbox, read the content and move the information to the PST file. 
     

    However, I understand the data is very important for you; therefore I suggest you copying all mails on the server into the local pst file or transfering there OST files manually. Thanks for your time and understanding!

     

    Hope the above information helpful!

    Andy

    Monday, August 17, 2009 6:25 AM

All replies

  • Firstly, we should understand the OST file is an offline folder file in Microsoft Outlook. Offline folders make it possible for the user to work offline and then to synchronize changes with the Exchange server the next time they connect. The ability to work offline is useful in environments with limited or unreliable connectivity.

     

    Maintaining changes to OST files within shadow copies is expensive in terms of space and I/O activity. The time-consuming work at backup time is backing up the OST files as part of the image. Everyday I/O will write to the OST file when Outlook is running. So the backup process will impact the performance on the computer. If the OST changes were kept in shadow copies, then Outlook writes to the OST files is copy on write I/O hit (2 writes, 1 read)every time. Even though we have worked to reduce the impact of copy-on-writes on shadow copies, a heavily churned file such as OST file still cause problems on the computer. In addition, the OST files can be regenerated. We delete OST file from the shadow copy before the image is created. For example, after restoring an OST, the computer detect a new version of the OST file on the computer, it will force you to delete, and the regenerate the local OST file. Therefore, it is still preferable to regenerate an OST file instead of restoring it.

     

    So, Backup the OST files is needless. If we backup the OST files on the computer, after restoring it by using the backup files, it will affect the computer stability and Outlook stability. If the computer restore it by using the old backup files, when starting Outlook, it will detect the computer has a old version, it will force you to delete the backup one, and then it will regenerate a new one on the computer. The Outlook will use the new one to startup normally.

    Thursday, August 13, 2009 10:39 AM
  • Thanks for taking the time to respond.  Your response was very thorough and helped me understand the reason behind why for most people backup of the OST file is not desirable.

    There is one thing I disagree with in my particular case (but not necessarily universally):

    "So, Backup the OST files is needless."

    There are two reasons why having a periodic backup of offline files, stored independendantly may be useful:
    1. the user deletes an email(s) accidentally

    2. the server deletes an email(s) in error

    In my case, Live Mail had a server error which deleted years of valuable personal emails.  The local cache was updated before I discovered the issue and there was no recourse to retrieve them.

    So, I think my solution will either to try to hack the backup tool to include OST files or just periodically save a copy of the cache myself manually.

    I think I learned an important lesson on taking the cloud for granted.
    • Proposed as answer by Brian Borg Friday, August 14, 2009 1:26 AM
    • Marked as answer by Dale QiaoModerator Wednesday, August 19, 2009 1:42 AM
    Thursday, August 13, 2009 5:38 PM
  • According to your description, you have a concern about what we should do if the emails were lost unexpected. Give this situation, we can turn on the AutoArchive in Outlook 2007 to achieve this efficiency. Use this method, we can backup our old emails. Outlook turns on AutoArchive by default to automatically archive old items on a set schedule. Outlook archives the following items:

     

    Outbox items older than three months

    Sent and Deleted items older than two months

    All other items including the Inbox, Calendar, Tasks, Notes, Journals and Drafts older than six months.

     

     

    We can follow the below link to set the configuration on How to Archive Outlook Email:

     
    How to Archive Outlook Email

    Friday, August 14, 2009 10:06 AM
  • Hello customer,

     

    By default, the .ost file is related to Exchange Server and is associated with a mailbox on the Exchange server. I would like you to know Microsoft does not offer the solution to open the orphan OST file due the security issues. To keep the OST secure, Exchange and Outlook store a key derived from the mailbox's unique entry ID as part of the user's profile. If the user's profile doesn't point to that particular mailbox, the user can't unlock the OST. There is no method to open the standalone OST file directly in Outlook since it is encrypted with the Exchange server mailbox. You need to connect the OST file to the original Exchange mailbox, read the content and move the information to the PST file. 
     

    However, I understand the data is very important for you; therefore I suggest you copying all mails on the server into the local pst file or transfering there OST files manually. Thanks for your time and understanding!

     

    Hope the above information helpful!

    Andy

    Monday, August 17, 2009 6:25 AM
  • Apparently I had big major wrong assumption on Outlook and Windows Backup. First, outlook says the deleted item is in deleted items folder and it is not - it is permanently deleted even though I didn't press the shift key I deleted my contact folder (not contact group or contact item). Second, windows backup didn't backup all the files.

    I read some of the feedback with lots of disappointment. Just to highlight some

    "......So, Backup the OST files is needless....Maintaining changes to OST files within shadow copies is expensive in terms of space and I/O activity. The time-consuming work at backup time is backing up the OST files as part of the image. Everyday I/O will write to the OST file when Outlook is running. So the backup process will impact the performance on the computer...... If the computer restore it by using the old backup files, when starting Outlook, it will detect the computer has a old version, it will force you to delete the backup one, and then it will regenerate a new one on the computer. The Outlook will use the new one to startup normally........"

    1) it is not needless - if I happen to have the OST file even one from a few weeks ago, I could have go offline to recover few hundreds of the contacts I deleted. Because exchange server was updated instantly and the deleted items are not in deleted items folder, I have no way to recover my contact list.

    2) all backups by default are redundant, consume space, consume bandwidth, takes time, etc,....but backup exist for a reason and it is worth the effort, space, bandwidth, time, etc to do that so that we can and able to recover from damage made unintentionally. Compare to the amount of family pictures, home video and other work stuff, this OST is nothing in terms of file size and bandwidth needed. Frankly, I don't mind that at all.

    3) it doesn't matter what a file is used for, how it is being used or who can used it, etc. Every file has their purpose and hence every file needs and must be backup for that purpose. This is so that one can undo and recover tools, settings, information accordingly.

    I only realize this horror after searching few hundreds of windows backup zipped folders without a single ost file in it. I hope next windows or next SP will have this addressed.

    Monday, October 24, 2011 9:06 AM
  • I'd like add to your experience with an example of why a complete backup should include all files, including ost, unless they are explicitly excluded. I completely agree with the points made in the post by chanfl

    I migrated from SBS 2000 with Exchange to SBSe with Office 365. I keep my deleted files for reference but apparently didn't understand the retention policy for the new hosted Exchange service. I just discovered that I am missing 6 months of archived (deleted) emails.

    Contrary to the information provided below, ost files can be can be easily converted to pst files with several utilities.

    I expected that my data was secure in the ost files in my SBSe backup files. You can imagine my anger and frustration when I found that Microsoft had excluded ost backup without notification. I have one independent Acronis backup for part of that period that allowed me to recover 3 months of data. The rest of my users are out of luck. Not good.

    Tuesday, March 27, 2012 5:26 PM
  • Totally agree with chanfl.

    Is a great mistake not to include the file .OST in the backup.

    I have lost hundreds of mail rules that I have set up for years.

    The mail rules are stored in the .OST file.


    • Edited by theremigue Monday, October 7, 2013 6:17 PM
    • Proposed as answer by ASW821 Sunday, April 27, 2014 7:33 PM
    • Unproposed as answer by ASW821 Sunday, April 27, 2014 7:33 PM
    Monday, October 7, 2013 6:16 PM
  • I think I have a solution to this annoying problem. There's a file exclusion list hidden in the registry.

    Find this key:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot

    Delete the OutlookOST key or just rename *.ost to *.xxx (just in case you ever want to change it back).

    All my .ost files now get backed up every time!

    Sunday, April 27, 2014 7:48 PM
  • Oct 9th and just learned the hard way that Microsoft has no warnings in their backup program about OST files not being backed up and apparently has no clue why this is so important to so many users.

    Will test the registry hack suggested in this blog.   But I will probably have to hack my way into the orphaned OST file? 

    This issue has been posted since 2009 and MS still does not post any warnings in their useless backup program. 


    • Edited by pcrudyII Thursday, October 9, 2014 8:36 PM
    Thursday, October 9, 2014 8:31 PM
  • Apparently I had big major wrong assumption on Outlook and Windows Backup. First, outlook says the deleted item is in deleted items folder and it is not - it is permanently deleted even though I didn't press the shift key I deleted my contact folder (not contact group or contact item). Second, windows backup didn't backup all the files.

    I read some of the feedback with lots of disappointment. Just to highlight some

    "......So, Backup the OST files is needless....Maintaining changes to OST files within shadow copies is expensive in terms of space and I/O activity. The time-consuming work at backup time is backing up the OST files as part of the image. Everyday I/O will write to the OST file when Outlook is running. So the backup process will impact the performance on the computer...... If the computer restore it by using the old backup files, when starting Outlook, it will detect the computer has a old version, it will force you to delete the backup one, and then it will regenerate a new one on the computer. The Outlook will use the new one to startup normally........"

    1) it is not needless - if I happen to have the OST file even one from a few weeks ago, I could have go offline to recover few hundreds of the contacts I deleted. Because exchange server was updated instantly and the deleted items are not in deleted items folder, I have no way to recover my contact list.

    2) all backups by default are redundant, consume space, consume bandwidth, takes time, etc,....but backup exist for a reason and it is worth the effort, space, bandwidth, time, etc to do that so that we can and able to recover from damage made unintentionally. Compare to the amount of family pictures, home video and other work stuff, this OST is nothing in terms of file size and bandwidth needed. Frankly, I don't mind that at all.

    3) it doesn't matter what a file is used for, how it is being used or who can used it, etc. Every file has their purpose and hence every file needs and must be backup for that purpose. This is so that one can undo and recover tools, settings, information accordingly.

    I only realize this horror after searching few hundreds of windows backup zipped folders without a single ost file in it. I hope next windows or next SP will have this addressed.

    I also have an Issue that required a restore to a previous OST to Export Item to PST for reimport into an exchange Mailbox for

    1. removal of Unidentified Duplicate Emails via 3rd party tools about 47k items.

    2. Recovery of Missing/ Unchecked Follow-up Items.

    3. Restoration of Items into a New Blank Mailbox created for the affected User.

    It is paramount that the System Image contain All system Critical Files... I.E. an Exchange server Fails or Database becomes unusable sat due to a Critical RAID Failure. Being able to Export The OST to PST from the Client is Critical to Recovering Items into the database if a backup of the server is unavailable of corrupt. Or in My case the Exchange server mailbox is full of erroneous items that cannot be easily removed.

    If you require additional reasons please do not hesitate to respond..

    Wednesday, July 20, 2016 7:30 AM
  • You cannot convert a OST file to a PST directly, There is security in place that ties the Exchange mailbox,OST file and MAPI profile together. That means that you need the be loged in with the original MAPI profile in order to open the OST file, if you can do that you can simply export or copy all data to a PST file.

    vISIT AT ; http://www.osttopstapp.com/

    Tuesday, December 4, 2018 5:38 AM