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Setting the Record Straight on vSphere 5.1 Backup and Recovery Support

There has been a fair amount of conversation and blog posts regarding an issue with the VMware Virtual Disk Development Kit (VDDK) for vSphere 5.1 that may cause backup and restore operations to hang or fail. This is no surprise considering successful backup and recovery of virtual machines is mission-critical to many organizations.

To provide a better understanding, let’s first take a brief look at how the VDDK is utilized by many virtual machine backup and recovery solution vendors: These vendors are permitted to repackage VDDK binaries as part of their solution (provided they sign a redistribution agreement). As new versions of the VDDK are released, backup and recover vendors update their software to include and utilize the new VDDK binaries to protect virtual machines running on the latest versions of vSphere.

VMware naturally released the VDDK 5.1 binaries with vSphere 5.1 to ensure continuity in backup and recovery support via third-party solutions. Shortly after this release, some backup partners reported bugs with the APIs. From the moment these bugs were discovered, VMware has been working and continues to work with impacted partners to enable support for vSphere 5.1 platform by leveraging the VDDK 5.0 U1 APIs. This helps ensure that customers can continue to confidently backup and successfully restore data in their VMware environments. Fixes for the reported issues have been identified and will soon be addressed in an updated version of VDDK 5.1. In the meantime, it is recommended you contact your backup partner simply to verify their vSphere 5.1 support statement.

VMware KB article: http://kb.vmware.com/kb/2039931

More information on VDDK: http://www.vmware.com/support/developer/vddk/


12 thoughts on “Setting the Record Straight on vSphere 5.1 Backup and Recovery Support

  1. Pingback: Symantec NetBackup now (partially) supports vSphere 5.1 | viktorious.nl – Virtualization & Cloud Computing

  2. Steve Ballmer

    Does this mean we should be OK backing up with Backup Clients that support VDDK 5.0 U1 to backup vSphere 5.1 VM’s?

    1. Jeff HunterJeff Hunter Post author

      We certainly cannot commit to a date, but hopefully in the next few months. As mentioned in the article, check with your backup software vendor for clarity on what is currently supported – many vendors have support for vSphere 5.1 in spite of the bug that was discovered.

  3. wrusman

    We are also frustrated with the waiting for this problem to be solved.
    This issue is reported in december 2012, we are now May 2013, that is almost 6 months ahead..

    We had to postpone some of our projects because we cannot upgrade to vSphere 5.1 until this issue is fixed, and these projects are still on hold 6 months later.

    I’m getting the feeling we’ll be lucky if this will be solved somewhere before vSphere 6 is launched

  4. Matthias Zahn


    it’s possible to backup VM’s using VDDK without CBT ? Commvault f.e. is not aware of this feature an will always turn on CBT. If CBT is disabled inside an VMX file, the backup will fail. If this possible, please made better hints at VDDK programming reference.

    The are issues with a master VM’s for VMware View “Linked Clones”, if CBT been activated.


    Matthias Zahn

  5. Nyle Landas

    SEP SESAM still reports issues with using 5.1 and requires the use of 5.0 for reliable backups. SEP has shown to be a reliable developer who makes regular changes to its software to keep up with industry changes in APIs.

    Is it possible that the flaws are in the VDDKs 5.1 API and not on the backup vendors side? Since 5.1.1 seems to have resolved some issues with vendors this circumstantially seems plausible. As such, how much longer before there is a fix for this major issue reported back in December of 2012?

    1. Nyle Landas

      Since VMWare KB seems to say this is caused by

      “Hang in connect or cleanup due to intermittent race condition.

      Windows processes can sometimes hang when calling VixDiskLib_ConnectEx() or VixDiskLib_Cleanup() due to a race condition while loading or unloading libraries. There is no known workaround.”


      This would add additional credence to my theory that this is an issue that VMware needs to address with 3rd part backup vendors.

      Who owns VMware again? I’d hate to imply anything with the question but do EMC backup solutions work correctly with VDDK 5.1.1?

      1. Jeff HunterJeff Hunter Post author

        As you can see here…


        …some issues have been addressed in VDDK 5.1.1 (link included for the benefit of other readers).

        Additional items are likely to be addressed in the next release of VDDK. As with any “roadmap” item, I cannot comment on specifics such as exactly what will be addressed and when, but the goal is to get several known issues taken care of very soon. It will then be up to the backup vendors as to how quickly these fixes get implemented in each vendor’s respective product(s).

        Backup and recovery vendors utilize the VDDK components and APIs in various ways. While it is true EMC owns a large number of VMware equities, it is best to look to the backup and recovery vendors, such as EMC, for specifics and support on their respective products.


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