November 11, 2010 at 12:13 am
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
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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
November 11, 2010 at 1:59 am
Do you use file compression on the NAS where the backups get corrupted?
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This thing is addressing problems that dont exist. Its solution-ism at its worst. We are dumbing down machines that are inherently superior. - Gilfoyle
November 12, 2010 at 2:35 am
Hi Henrico
Thanks for your response. I'm a business analyst and unfortunately not very technical. However, I have run this past our technical specialist, and this is the answer he came up with:
I have just got off the phone with SNAP support. They have confirmed that there are no settings for data/file compression on the SNAP server. The server basically gives raw disk to the clients.
The only thing that he suggested we check is the file attributes to see if they are being affected/changed by the copying or backup process.
I have included all the details of the SNAP server and configuration.
SNAP Server details:
Model: 18000 Software: 5.1.046 Hardware: 06.00.00 Server # 900246 BIOS: SN73B03
Storage: Head Unit (1800 - 8 drives - total 1.83TB), Expansion Unit1 (SD30SA – 16 drives – 3.65TB), Expansion Unit2 (SD30SA – 16 drives – 3.65TB)
Volume configuration for sage-bi / actrolsql
6 * 234GB drives in RAID 5 – 1.13TB usable (810.25GB currently free)
One volume – BUVOL0
Two shares – backup_sage & backup_sma
Access Security: Full access to Domain Admins & Snap admins (everything else denied)
Allowed Access protocols for shares: SMB-NFS-AFP-HTTP-FTP
Please let me know if you have any further questions - we may actually get our technical specialist jumping in on this thread to communicate with you directly.
Thanks very much
Regards
Ina
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