[Qemu-devel] [Bug 1477538] [NEW] Windows QEMU Guest Agent VSS Provider service stops during qemu backup

[Joop Martens]

Public bug reported:

I’m currently implementing the QEMU Guest Agent on all my KVM Windows
guests.

I’m using the stable VirtIO drivers and Guest agent from Fedora:
https://fedoraproject.org/wiki/Windows_Virtio_Drivers

Both the stable and latest release do provide Qemu Windows Guest agent
7.0.0.10.

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.
Operation:
   Gathering Writer Data
Context:

   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 7.0.0.10

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1477538

Title:
  Windows QEMU Guest Agent VSS Provider service stops during qemu backup

Status in QEMU:
  New

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

  I’m using the stable VirtIO drivers and Guest agent from Fedora:
  https://fedoraproject.org/wiki/Windows_Virtio_Drivers

  Both the stable and latest release do provide Qemu Windows Guest agent
  7.0.0.10.

  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.
  Operation:
     Gathering Writer Data
  Context:

     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 7.0.0.10

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