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Corruption on .abf files RRS feed

  • Question

  • Good day,

    We back up our Analysis Services cubes to a NAS, and have recently found that all our backups have become corrupted.  We have done testing, and found the following:

    If we create an .abf backup of an OLAP cube on the local HDD and test restore the backup, it restores successfully.  We then move the backup file to the NAS as this is our usual backup storage area.  When it is required to restore a backup, we copy the backup file back to the local HDD for restore.  At this point, the restore fails with the following error message:

    TITLE: Microsoft SQL Server Management Studio

    ------------------------------

    Errors in the compression library: The data could not be decompressed.

    (Microsoft.AnalysisServices)


    We know now that it is the particular location that we backed the files up to that causes this corruption, as we can consistently replicate this.  We now back up to a different location which we have tested, and confirmed that this location do not cause corruption.  (Interesting point aside is that this network location does not seem to corrupt .bak files - they still restore successfully after being retrieved from this location.  It only seems to affect .abf files)

    The problem that we have is that we lost one of our cubes and need to be able to restore from one of our .abf backup files, but they are all corrupted because they have been copied to this location.   Is there any way in which a corrupt .abf file can be recovered?  In order to assist in troubleshooting I have created two copies of an .abf backup of the AdventureWorks 2005 OLAP cube.  One file was copied to the network location (causing the corruption) and one was left to be a good backup.  We can now verify that on a number of SQL Server instances we can successfully restore the good backup, and consistently get the same error on the corrupt backup.  The only difference between the two is the fact that one was briefly copied to the problem network location.

    We can upload these files somewhere if anyone can test and possibly suggest a solution.

    Regards

    Ina

    Thursday, November 11, 2010 6:58 AM

Answers

  • I suspect that you will need to contact Microsoft support for this, though you will probably have to pay as this does not appear to be an issue with Analysis Services.

    You could possibly compare the the two .abf files (i.e. the good versus the corrupt) to see what has changed. It could be that a couple of bytes at the header of the file etc. may have been changed by the NAS and as such you could try and reverse the corruption. However, I caution you that this could be construed as "reverse engineering" which is specifically prohibited by Microsoft so best check with them.

    It might also be worth investigating whether or not your NAS places special meaning on .abf files. Does the NAS maybe think a .abf file is some file that it needs to act on during a copy operation or something, or is it that a particular area of the NAS is corrupt and that these .abf files always get copied to the same location?


    http://bi-logger.blogspot.com/
    • Marked as answer by Raymond-Lee Saturday, November 20, 2010 3:49 AM
    Thursday, November 11, 2010 8:17 PM

All replies

  • I suspect that you will need to contact Microsoft support for this, though you will probably have to pay as this does not appear to be an issue with Analysis Services.

    You could possibly compare the the two .abf files (i.e. the good versus the corrupt) to see what has changed. It could be that a couple of bytes at the header of the file etc. may have been changed by the NAS and as such you could try and reverse the corruption. However, I caution you that this could be construed as "reverse engineering" which is specifically prohibited by Microsoft so best check with them.

    It might also be worth investigating whether or not your NAS places special meaning on .abf files. Does the NAS maybe think a .abf file is some file that it needs to act on during a copy operation or something, or is it that a particular area of the NAS is corrupt and that these .abf files always get copied to the same location?


    http://bi-logger.blogspot.com/
    • Marked as answer by Raymond-Lee Saturday, November 20, 2010 3:49 AM
    Thursday, November 11, 2010 8:17 PM
  • Did you ever get a resolution to this. We are seeing a similar issue.

    Justin Cervero - MS Enterprise Admin - Appalachian State University

    Friday, September 25, 2015 3:47 PM