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Outlook 2010 on 2 computers (cached mode) showing huge difference in outlook.ost file size. RRS feed

  • Question

  • Exchange 2003, outlook 2010 on a PC and a laptop configured to the same user mailbox.  Pretty much the same configuration on both.  The PC has an outlook.ost file that is 28GB and the laptop's ost file is 6GB.  

    Why would the file sizes be so hugly different going against the same mailbox?  All settings are identical (what to cache etc.)


    Friday, June 2, 2017 1:22 PM

All replies

  • was the profile with  the small ost created recently? the large ost may need compacted - outlook should do it automatically but sometimes doesnt. 


    Diane Poremsky [MVP - Outlook]
    Outlook & Exchange Solutions Center
    Outlook Tips
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    Sunday, June 4, 2017 5:20 PM
  • Hi,

    Please first try compacting the bigger OST file as Diane suggested via Account Settings > Data Files tab, highlighting your OST file, clicking Settings > Advanced tab > Outlook Data File Settings > Compact Now.

    In addition to Diane's suggestion, do you have any shared folder (shared mail folder, calendars) opened on one of the PCs? It could be that the contents of the shared/subscribed shared folders are also been cached to the same OST file.

    Regards,

    Steve Fan


    Please remember to mark the replies as answers if they helped.

    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    • Proposed as answer by Steve Fan Monday, June 12, 2017 9:28 AM
    Monday, June 5, 2017 6:34 AM
  • Hi,

    Please first try compacting the bigger OST file as Diane suggested via Account Settings > Data Files tab, highlighting your OST file, clicking Settings > Advanced tab > Outlook Data File Settings > Compact Now.

    In addition to Diane's suggestion, do you have any shared folder (shared mail folder, calendars) opened on one of the PCs? It could be that the contents of the shared/subscribed shared folders are also been cached to the same OST file.

    Regards,

    Steve Fan


    Please remember to mark the replies as answers if they helped.

    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    I think you may have found my problem.  No shared folders, but... I have 3 other users mailboxes that are sitting in my left hand window which automatically open with "Open these additional mailboxes" option.  Can I avoid caching these mailboxes into my OST by un-checking the "download shared folders" option?  What happens if I go to those mailboxes in outlook?  Does it treat it as a non-cache client/server experience?  I rarely go to those mailboxes, but there are times where I need to have access.

    ----update----

    I unchecked the "download shared folders" option, cleared out the Outlook directory and re-launched Outlook.  It started up as "setting up for first time" and re-downloaded all mail from the server.  This time I got a 3.6GB OST instead of a 28GB OST.  Clearly it didn't download the 3 mailboxes that I auto open.  I was able to access those MBX's without my OST growing any larger.

    Roveer

    • Edited by Roveer Monday, June 5, 2017 8:56 PM
    • Proposed as answer by Steve Fan Monday, June 12, 2017 9:28 AM
    Monday, June 5, 2017 3:49 PM
  • Hi Roveer,

    Sorry for the delay. It looks the issue has been fixes, right? Hope it's not too late to answer this question:

    What happens if I go to those mailboxes in outlook?  Does it treat it as a non-cache client/server experience?

    Re: You will be still able to access these shared mailboxes. When these mailboxes are not cached to your OST file, you are accessing the mailbox data directly when viewing the mailboxes. It could be slower that cached mode according to your network status. However it doesn't matter if you rarely go to those mailboxes :)

    By the way, do you mind to help mark the reply that helps as the answer, so that it will benefit other community members who encounter the same issue? Thank you for your understanding.

    Regards,

    Steve Fan


    Please remember to mark the replies as answers if they helped.

    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    • Proposed as answer by Steve Fan Friday, June 23, 2017 9:54 AM
    Monday, June 12, 2017 9:27 AM