Backup & Recovery

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  • 1.  VDR Error 3946 (disk open failed)

    Posted Aug 27, 2010 06:33 AM

    Good day!

    I have an issue lately with VDR 1.2 :

    When is trying to backup into 2 servers of mine (11 in total) it shows the following error :


    8/27/2010 2:54:20 AM: Performing full back up of disk "[N3300-Up] Fileserver/Fileserver-000007-flat.vmdk" using "Network"

    8/27/2010 5:21:20 AM: File "Alpha Tankers & Freighters/Alpha/host/Alpha Cluster/Resources/Fileserver/Fileserver_1-000010-flat.vmdk": can't read, error -3946 ( disk open failed)

    8/27/2010 5:21:20 AM: Trouble reading files, error -3946 ( disk open failed)

    8/27/2010 6:02:36 AM: Task incomplete

    8/27/2010 6:02:36 AM: Remaining: 2 files, 200,1 GB

    8/27/2010 6:02:36 AM: Completed: 5 files, 50,1 GB

    8/27/2010 6:02:36 AM: Performance: 2713 MB/minute

    8/27/2010 6:02:36 AM: Duration: 03:46:17 (00:37:34 idle/loading/preparing)


    My setup i suppose is quite simple. I have one VDR appliance (i have also recreated it but with no luck) to take the backups and store it to Network Shares (on a QNAP Nas server and on External HD drive).

    I have tried to create new shares on other servers but still the same error occurs. The strange is that the problem is occuring only on the two fileservers i have and apparently on the second virtual disk declared which is used for data storage reasons only (i keep only the OS in the first one)...

    Any ideas?

    Thank you in advance,



  • 2.  RE: VDR Error 3946 (disk open failed)

    Posted Aug 27, 2010 06:37 AM

    Check that the block size of the VMFS where VDR appliance resides is equal or greater than VMFS of fileserver VMDK.

    Ole Thomsen

  • 3.  RE: VDR Error 3946 (disk open failed)

    Posted Aug 27, 2010 09:05 AM

    Thanks Olen for your reply,

    Both VM resides on my Netapp External storage that has block size of 4 MB while the fileserver VMDK is of 210 GB. Does it seem ok to you?

    The datarecovery though is taking the backups into network shared folders, should i check smt from there?

    Thank you in advance



  • 4.  RE: VDR Error 3946 (disk open failed)

    Posted Aug 27, 2010 09:19 AM

    If the VMs are located on 4MB blocksize storage, you should check that the storage from which the VDR appliance is running (the OS vmdk) has at least 4MB blocksize.

    A quick way to test is moving the VDR to run from same storage as the fileserver. Then blocksize will not be a part of the equation.

    Ole Thomsen