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PST file format has changed in Outlook 2013 RRS feed

  • Question

  • I noticed that the PST file format has changed in Outlook 2013 (e.g., wVer is now 35 instead of 23, the node size now 0x1000 instead of 0x200, ...).

    My question is, will the [MS-PST] file format spec be updated to document these changes, and if so, when?

    Thanks, Phillip.

    Monday, October 21, 2013 11:04 PM

Answers

  • Hi Phillip, while the .OST file format shares a lot of similarities with the .PST file format, they are not the same. The MS-PST document should not be used as a reference for .OST files. The .OST file format is not covered by the Open Specifications documentation.


    Josh Curry (jcurry) | Escalation Engineer | Open Specifications Support Team

    Friday, October 25, 2013 4:43 PM
    Moderator
  • Hi Phillip, we cannot predict what future changes might be made to any given file format. However, any changes that are made to a file format that is covered under the Open Specification Promise will be documented.


    Josh Curry (jcurry) | Escalation Engineer | Open Specifications Support Team

    Tuesday, June 3, 2014 9:50 PM
    Moderator

All replies

  • Hi Phillip, thank you for your question. A member of the protocol documentation team will respond to you soon.


    Josh Curry (jcurry) | Escalation Engineer | Open Specifications Support Team

    Tuesday, October 22, 2013 12:43 AM
    Moderator
  • Hi Phillip, I created a new PST with the version of Outlook that I am using, 15.0.4535.1508, 32-bit, and the wVer property is set to 0x0017, or 23, which is what I would expect.

    Also, I assume by 'node size' you actually mean the size of Pages that are used in the NDB layer? I checked these in my file and I see that they are 512 bytes, which is what I would expect.

    Can you provide some additional information about the .PST file you are looking at? How was it created? Was it created by Outlook?


    Josh Curry (jcurry) | Escalation Engineer | Open Specifications Support Team

    Wednesday, October 23, 2013 7:24 PM
    Moderator
  • Hi Josh,

    Thanks for your response.  Those are good questions.  I actually have an OST not a PST.  Also, I'm not exactly sure where it came from yet, but I will try to find out.  (I got it from a co-worker.)

    Yep, I am talking about the pages at the NDB layer.  In this OST, they are definitely 4K instead of 512 bytes.

    The other main difference I'm seeing is some (most?) of the Blocks are compressed.

    Wednesday, October 23, 2013 10:48 PM
  • Hi Phillip, while the .OST file format shares a lot of similarities with the .PST file format, they are not the same. The MS-PST document should not be used as a reference for .OST files. The .OST file format is not covered by the Open Specifications documentation.


    Josh Curry (jcurry) | Escalation Engineer | Open Specifications Support Team

    Friday, October 25, 2013 4:43 PM
    Moderator
  • Hi Josh,

    Thanks for the help so far.  I wish I knew more about how this OST was made, but all I could find out was it came from a Windows 8 machine, possibly after an unclean shutdown.  But I wouldn't call it "corrupt" by any means.  It very much looks like a new version of the file format.

    However, like you, I did a test of my own with Outlook 2013, and both the OST it made and a PST I made with it are using wVer 23 like normal.  So I have no idea how to reproduce an OST or PST with wVer 35.

    I realize OST and PST are not identical, e.g., the top-level folder is 0x122 instead of 0x21, but at the NDB layer at least from my experience they are pretty much identical.

    If you have any more insight as to how an OST or PST could be created with wVer 35, and whether or not I might encounter another one in the future, it would be greatly appreciated.

    Thanks, Phillip

    Tuesday, October 29, 2013 6:51 PM
  • FYI, I have now encountered an OST with wVer of 36.  It appears to have the same changes as I saw in wVer 35 last year (4K pages and compressed blocks).

    Question: Will PST files ever adopt these changes too, and if so, will it be documented in MS-PST white paper?

    Thanks, Phillip

    Thursday, May 29, 2014 8:43 PM
  • Hi Phillip,

    Thank you for this inquiry. One of our team members will review this and follow-up soon.

    Regards,

    Edgar

    Thursday, May 29, 2014 9:20 PM
    Moderator
  • Hi Phillip, we cannot predict what future changes might be made to any given file format. However, any changes that are made to a file format that is covered under the Open Specification Promise will be documented.


    Josh Curry (jcurry) | Escalation Engineer | Open Specifications Support Team

    Tuesday, June 3, 2014 9:50 PM
    Moderator
  • Hi Philip, 

    Are you still looking for all the differences in OST2013?  I have figured out most (if not all) of it including compression. 

    Matt(hew.janda at hotmail dot com)


    • Edited by Matt Janda Wednesday, September 10, 2014 5:35 PM
    Wednesday, September 10, 2014 5:34 PM
  • Hi,

    At some point I will be releasing document with all differences in OST2013. Some donation will be required to cover my expenses for late night coffees :)

    The document will cover only the differences so I assume you have got already previous OST/PST versions covered.  

    If you are trying to solve it on your own I can give you few hints...

     

    The major changes were made in followings: 

    Heap-on-Node (HID)
    B-Tree page (BTPAGE)
    Leaf BBT Entry (BBTENTRY)
    Data Blocks (compression)

    Best Regards,

    Matt

    Friday, September 12, 2014 9:50 AM