Missing Hyper-V Service Connection Point caused failed off-host backup proxy jobs

The issue

We have a largish Windows Server 2016 Hyper-V cluster (9 nodes) that is running a smooth as can be but for one issue. The off-host backups with Veeam Backup & Replication v9.5 (based on transportable hardware snapshots) are failing. They only fail for the LUNs that are currently residing on a few of the nodes on that cluster. So when a CSV is owned by node 1 it will work, when it owned by node 6 it will fail. In this case we had 3 node that had issues.

As said, everything else on these nodes, cluster wise or Hyper-V wise was working 100% perfectly. As a matter of fact, they were the perfect Hyper-V clusters we’d all sign for. Bar that one very annoying issue.

Finding the cause

When looking at the application log on the off-host backup proxy it’s quite clear that there is an issue with the hardware VVS provider snapshots.

We get event id 0 stating the snapshot is already mounted to different server.

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Followed by event id 12293 stating the import of the snapshot has failed

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When we check the SAN, and monitor a problematic host in the cluster we see that the snapshot was taken just fine. what was failing was the transport to the backup repository server. It also seemed like an attempt was made to mount the snapshot on the Hyper-V host itself, which also failed.

What was causing this? We dove into the Hyper-V and cluster logs and found nothing that could help us explain the above. We did find the old very cryptic and almost undocumented error:

Event ID 12660 — Storage Initialization

Updated: April 7, 2009

Applies To: Windows Server 2008

This is preliminary documentation and subject to change.

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This aspect refers events relevant to the storage of the virtual machine that are caused by storage configuration.

Event Details

Product:

Windows Operating System

ID:

12660

Source:

Microsoft-Windows-Hyper-V-VMMS

Version:

6.0

Symbolic Name:

MSVM_VDEV_OPEN_STOR_VSP_FAILED

Message:

Cannot open handle to Hyper-V storage provider.

Resolve

Reinstall Hyper-V

A possible security compromise has been created. Completely reimage the server (sometimes called a bare metal restoration), install a new operating system, and enable the Hyper-V role.

Verify

The virtual machine with the storage attached is able to launch successfully.

This doesn’t sound good, does it? Now you can web search this one and find very little information or people having serious issues with normal Hyper-V functions like starting a VM etc. Really bad stuff. But we could start, stop, restart, live migrate, storage live migrate, create checkpoints etc. at will without any issues or even so much as a hint of issues in the logs.

On top of this event id Event ID 12660 did not occur during the backups. It happens when you opened up Hyper-V manager and looked at the setting of Hyper-V or a virtual machine. Everything else on these nodes, cluster wise or Hyper-V wise was working 100% perfectly Again, this is the perfectly behaving Hyper-V cluster we’d all sign for. If it didn’t have that very annoying issue with a transportable snapshot on some of the nodes.

We extended our search outside if of the Hyper-V cluster nodes and then we hit clue. On the nodes that owns the LUN that was being backup and that did show the problematic transportable backup behavior noticed that the Hyper-V Service Connection Point (SCP) was missing.

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We immediately checked the other nodes in the cluster having a backup issue. BINGO! That was the one and only common factor. The missing Hyper-V SCP.

Fixing the issue

Now you can create one manually but that leaves you with missing security settings and you can’t set those manually. The Hyper-V SCP is created and attributes populates on the fly when the server boots. So, it’s normal not to see one when a server is shut down.

The fastest way to solve the issue was to evacuate the problematic hosts, evict them from the cluster and remove them from the domain. For good measure, we reset the computer account in AD for those hosts and if you want you can even remove the Hyper-V role. We then rejoined those node to the domain. If you removed the Hyper-V role, you now reinstall it. That already showed the SCP issue to be fixed in AD. We then added the hosts back to the cluster and they have been running smoothly ever since. The Event ID 12660 entries are gone as are the VSS errors. It’s a perfect Hyper-V cluster now.

Root Cause?

We’re think that somewhere during the life cycle of the hosts the servers have been renamed while still joined to the domain and with the Hyper-V role installed. This might have caused the issue. During a Cluster Operating System Rolling Upgrade, with an in-place upgrade, we also sometime see the need to remove and re-add the Hyper-V role. That might also have caused the issue. We are not 100% certain, but that’s the working theory and a point of attention for future operations.

Troubleshooting Veeam B&R Error code: ‘32768’. Failed to create VM recovery snapshot

I recently had to move a Windows Server 2016 VM over to another cluster (2012R2 to 2016 cluster)  and to do so I uses shared nothing live migration. After the VM was happily running on the new cluster I kicked of a Veeam backup job to get a first restore point for that VM. Better safe than sorry right?

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But the job and the retries failed for that VM. The error details are:

Failed to create snapshot Compellent Replay Manager VSS Provider on repository01.domain.com (mode: Veeam application-aware processing) Details: Job failed (‘Checkpoint operation for ‘FailedVM’ failed. (Virtual machine ID 459C3068-9ED4-427B-AAEF-32A329B953AD). ‘FailedVM’ could not initiate a checkpoint operation: %%2147754996 (0x800423F4). (Virtual machine ID 459C3068-9ED4-427B-AAEF-32A329B953AD)’). Error code: ‘32768’.
Failed to create VM recovery snapshot, VM ID ‘3459c3068-9ed4-427b-aaef-32a329b953ad’.

Also when the job fails over to the native Windows VSS approach when the HW VSS provider fails it still does not work. At first that made me think of a bug that sued to exist in Windows Server 2016 Hyper-V where a storage live migration of any kind would break RCT and new full was needed to fix it. That bug has long since been fixed and no a new full backup did not solve anything here. Now there are various reasons why creating a checkpoint will not succeed so we need to dive in deeper. As always the event viewer is your friend. What do we see? 3 events during a backup and they are SQL Server related.
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On top of that the SQLServerWriter  is in a non retryable error when checking with vssadmin list writers.

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It’s very clear there is an issue with the SQL Server VSS Writer in this VM and that cause the checkpoint to fail. You can search for manual fixes but in the case of an otherwise functional SQL Server I chose to go for a repair install of SQL Server. The tooling for hat is pretty good and it’s probably the fastest way to resolve the issues and any underlying ones we might otherwise still encounter.

After running a successful repair install of SQL Server we get greeted by an all green result screen.

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So now we check vssadmin list writers again to make sure they are all healthy if not restart the SQL s or other relevant service if possible. Sometime you can fix it by restarting a service, in that case reboot the server. We did not need to do that. We just ran a new retry in Veeam Backup & Replication and were successful.

There you go. The storage live migration before the backup of that VM made me think we were dealing with an early Windows Server 2016 Hyper-V bug but that was not the case. Trouble shooting is also about avoiding tunnel vision.

Optimizing Backups: PowerShell Script To Move All Virtual Machines On A Cluster Shared Volume To The Node Owing That CSV

When you are optimizing the number of snapshots to be taken for backups or are dealing with storage vendors software that leveraged their hardware VSS provider you some times encounter some requirements that are at odds with virtual machine mobility and dynamic optimization.

For example when backing up multiple virtual machines leveraging a single CSV snapshot you’ll find that:

  • Some SAN vendor software requires that the virtual machines in that job are owned by the same host or the backup will fail.
  • Backup software can also require that all virtual machines are running on the same node when you want them to be be protected using a single CSV snap shot. The better ones don’t let the backup job fail, they just create multiple snapshots when needed but that’s less efficient and potentially makes you run into issues with your hardware VSS provider.

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VEEAM B&R v8 in action … 8 SQL Server VMs with multiple disks on the same CSV being backed up by a single hardware VSS writer snapshot (DELL Compellent 6.5.20 / Replay Manager 7.5) and an off host proxy Organizing & orchestrating backups requires some effort, but can lead to great results.

Normally when designing your cluster you balance things out a well as you can. That helps out to reduce the needs for constant dynamic optimizations. You also make sure that if at all possible you keep all files related to a single VM together on the same CSV.

Naturally you’ll have drift. If not you have a very stable environment of are not leveraging the capabilities of your Hyper-V cluster. Mobility, dynamic optimization, high to continuous availability are what we want and we don’t block that to serve the backups. We try to help out to backups as much a possible however. A good design does this.

If you’re not running a backup every 15 minutes in a very dynamic environment you can deal with this by live migrating resources to where they need to be in order to optimize backups.

Here’s a little PowerShell snippet that will live migrate all virtual machines on the same CSV to the owner node of that CSV. You can run this as a script prior to the backups starting or you can run it as a weekly scheduled task to prevent the drift from the ideal situation for your backups becoming to huge requiring more VSS snapshots or even failing backups. The exact approach depends on the storage vendors and/or backup software you use in combination with the needs and capabilities of your environment.

Now there is a lot more to discuss, i.e. what and how to optimize for virtual machines that are clustered. For optimal redundancy you’ll have those running on different nodes and CSVs. But even beyond that, you might have the clustered VMs running on different cluster, which is the failure domain.  But I get the remark my blogs are wordy and verbose so … that’s for another time Winking smile

DELL Compellent Hardware VSS Provider & Commvault on Windows Server 2012 Hyper-V nodes – Volume Shadow Copy Service error: Unexpected error querying for the IVssWriterCallback interface. hr = 0x80070005, Access is denied.

As you know by now I’ve been building a high throughput, large volume Disk2Disk backup solution and that has been rather successful. At optimal speed we get 2TB/Hour per backup media server. As we currently have two, we can get to 4TB/hour at maximum throughput Smile. Currently that is, we’ll see if more is possible. The solution, which I’ll blog about later, is based on the Dell Compellent hardware VSS provider (Dell Compellent Replay Manager 6.2.0.9), Windows Server 2012, CommVault 9.0 R2 and PowerVault storage a the target disks and as it’s working now is saving us many hundred of thousands of Euros compared to dedicated D2D backup appliances or solutions.

The entire process has been a fairly smooth one, which was a relief as decent hardware VSS providers are not easy to come by, based on our experience and that of many colleagues. So, once again the DELL Compellent choice is turning out to be a good one. We did have to fix one small issue along the way.

Whilst using the DELL Compellent Hardware VSS Provider with Commvault Simpana 9.0 R2  to do host level back of the virtual machines on Windows Server 2012 Hyper-V cluster nodes. We ran into a small issue. The backup run fine but we saw this error being logged:

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: {3f4965d8-10ac-411b-bf6d-6a607f237775}

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The description found here was not helpful in resolving this. This error is found all over the internet with just about any backup product. The possible causes and solutions that are suggested are as follows:

Change the Language for non-Unicode programs to English (United States)

This is not a solution in our case, which would have surprised me if it had been.

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Eliminate the error condition by adding the access permissions for the domain account that the Compellent Replay Manager Service for Microsoft Servers (VSS) runs under to COM Security of the affected server

As the domain account used for this service is a member of the local administrators group that already has the permissions this would also have surprised me but we tested it anyway. It turns out this is not the cause either.

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But for your information this is how it’s done:

You can eliminate the error condition by adding the access permissions for the Network Service account to the COM Security of the affected server. To add the access permissions for the Network Service account, do the following:

  • From the Start Menu, select Run
    The Run dialog opens.In the Open field, input 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 DOMAINcompellentreplayservice account with Local Access & Remote access allowed (cluser => not just a local host).
  • Close all open dialogs.
  • Restart the computer.

The real cause & solution

According to Microsoft support this issue occurs when using a 3rd party backup program that utilizes Windows VSS (Volume Shadow Service) and has its own requestor. This is indeed the case here. “It looks like the requestor (the backup application) does not allow system writer to call back into their process and hence generates the error in the application log.” This sounds very plausible Winking smile

The fix:

  1. The following example grants access to the "DOMAINcompellentreplayservice" account.
  2. Click on Start, type regedit in the search box.
  3. On the Registry Editor window, navigate to: KEY_LOCAL_MACHINE>SYSTEM>CurrentControlSet>Services>VSS>VssAccessControl
  4. Add a DWORD value with the name: "DOMAINcompellentreplayservice" and set the value to “1”.

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And voila: the error has gone when running backups Open-mouthed smile

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I assume no responsibility if you do this in your environment but I can say that all this works perfectly in our CommVault Simpana 9.0 R2 setup whist backing up the virtual machines on our Hyper-V cluster nodes at the host level using the DELL Compellent hardware VSS provider. And yes this is Windows Server 2012, careful testing, planning helps when being an early adaptor.