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[Qemu-devel] [Bug 1477538] Re: Windows QEMU Guest Agent VSS Provider ser

From: Ravindra Teli
Subject: [Qemu-devel] [Bug 1477538] Re: Windows QEMU Guest Agent VSS Provider service stops during qemu backup
Date: Wed, 18 May 2016 14:20:35 -0000

Finally it worked.

I had to carry out DCOM config that you suggested earlier in addition to
installation of 7.2.1


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  Windows QEMU Guest Agent VSS Provider service stops during qemu backup

Status in QEMU:
  Fix Released

Bug description:
  I’m currently implementing the QEMU Guest Agent on all my KVM Windows

  I’m using the stable VirtIO drivers and Guest agent from Fedora:

  Both the stable and latest release do provide Qemu Windows Guest agent

  After the Guest agent installation I initially received VSS events
  with ID 8194:

   Volume Shadow Copy Service error: Unexpected error querying for the
  IVssWriterCallback interface.  hr = 0x80070005, Access is denied.

  This is often caused by incorrect security settings in either the writer or 
requestor process.
     Gathering Writer Data

     Writer Class Id: {e8132975-6f93-4464-a53e-1050253ae220}

     Writer Name: System Writer

     Writer Instance ID: {6c777a34-53dd-4fb3-a4c9-b85d7e183e27}

  I was able to fix this issue by adding local access permissions for
  the “Network Service” account at the Dcom security permissions:

  On the client computer from the Start Menu, select Run
  The Run dialog opens.
  In the Open field type dcomcnfg and click OK.
  The Component Services dialog opens.
  Expand Component Services, Computers, and My Computer.
  Right-click My Computer and click Properties on the pop-up menu.
  The My Computer Properties dialog opens.
  Click the COM Security tab.
  Under Access Permission click Edit Default.
  The Access Permissions dialog opens.
  From the Access Permissions dialog, add the "Network Service" account with 
Local Access allowed.
  Close all open dialogs.

  Now an initial backup runs without any errors but this is causing the
  QEMU Guest Agent VSS Provider service to stop running without any
  error in the event log.

  As a result a second backup will cause an error: MSDTC Client 2 with
  event ID: 4879:

  MSDTC encountered an error (HR=0x80000171) while attempting to
  establish a secure connection with system SERVERNAME.

  This is probably caused because the QEMU Guest Agent VSS Provider
  service isn’t running anymore.

  I can manually start the QEMU Guest Agent VSS Provider service but
  every backup is causing the service to stop.

  I’m seeing this behavior at all my Windows based guests running both
  Windows Server 2012 R2 and Windows Server 2008 R2.

   Since I can’t find any logging or troubleshooting possibilities for
  this particular service I'm open for suggestions how to troubleshoot
  this issue to receive detailed information about the reason why this
  services stops running during a backup.

  qemu-server   3.4-3    amd64
  Guest agent

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