Live Migration Fails due to non-existent SharedStoragePath or ConfigStoreRootPath

Introduction

I was tasked to troubleshoot a cluster where cluster aware updating (CAU) failed due to the nodes never succeeding going into maintenance mode. It seemed that none of the obvious or well know issues and mistakes that might break live migrations were present. Looking at the cluster and testing live migration not a single VM on any node would live migrate to any other node.
So, I take a peek the event id and description and it hits me. I have seen this particular event id before.

Live Migration Fails due to non-existent SharedStoragePath or ConfigStoreRootPath

Log Name:      System
Source:        Microsoft-Windows-Hyper-V-High-Availability
Date:          9/27/2018 15:36:44
Event ID:      21502
Task Category: None
Level:         Error
Keywords:
User:          SYSTEM
Computer:      NODE-B.datawisetech.corp
Description:
Live migration of ‘Virtual Machine ADFS1’ failed.
Virtual machine migration operation for ‘ADFS1’ failed at migration source ‘NODE-B’. (Virtual machine ID 4B5F2F6C-AEA3-4C7B-8342-E255D1D112D7)
Failed to verify collection registry for virtual machine ‘ADFS1’: The system cannot find the file specified. (0x80070002). (Virtual Machine ID 4B5F2F6C-AEA3-4C7B-8342-E255D1D112D7).

The live migration fails due to non-existent SharedStoragePath or ConfigStoreRootPath which is where collections metadata lives.

More errors are logged

There usually are more related tell-tale events. They however are clear in pin pointing the root cause.

On the destination host

On the destination host you’ll find event id 21066:

Log Name:      Microsoft-Windows-Hyper-V-VMMS-Admin
Source:        Microsoft-Windows-Hyper-V-VMMS
Date:          9/27/2018 15:36:45
Event ID:      21066
Task Category: None
Level:         Error
Keywords:
User:          SYSTEM
Computer:      NODE-A.datawisetech.corp
Description:
Failed to verify collection registry for virtual machine ‘ADFS1’: The system cannot find the file specified. (0x80070002). (Virtual Machine ID 4B5F2F6C-AEA3-4C7B-8342-E255D1D112D7).

A bunch of 1106 events per failed live migration per VM in like below:

Log Name:      Microsoft-Windows-Hyper-V-VMMS-Operational
Source:        Microsoft-Windows-Hyper-V-VMMS
Date:          9/27/2018 15:36:45
Event ID:      1106
Task Category: None
Level:         Error
Keywords:
User:          SYSTEM
Computer:      NODE-A.datawisetech.corp
Description:
vm\service\migration\vmmsvmmigrationdestinationtask.cpp(5617)\vmms.exe!00007FF77D2171A4: (caller: 00007FF77D214A5D) Exception(998) tid(1fa0) 80070002 The system cannot find the file specified.

On the source host

On the source host you’ll find event id 1840 logged
Log Name:      Microsoft-Windows-Hyper-V-Worker-Operational
Source:        Microsoft-Windows-Hyper-V-Worker
Date:          9/27/2018 15:36:44
Event ID:      1840
Task Category: None
Level:         Error
Keywords:
User:          NT VIRTUAL MACHINE\4B5F2F6C-AEA3-4C7B-8342-E255D1D112D7
Computer:      NODE-B.datawisetech.corp
Description:
[Virtual machine 4B5F2F6C-AEA3-4C7B-8342-E255D1D112D7] onecore\vm\worker\migration\workertaskmigrationsource.cpp(281)\vmwp.exe!00007FF6E7C46141: (caller: 00007FF6E7B8957D) Exception(2) tid(ff4) 80042001     CallContext:[\SourceMigrationTask]

As well as event id 21111:
Log Name:      Microsoft-Windows-Hyper-V-High-Availability-Admin
Source:        Microsoft-Windows-Hyper-V-High-Availability
Date:          9/27/2018 15:36:44
Event ID:      21111
Task Category: None
Level:         Error
Keywords:
User:          SYSTEM
Computer:      NODE-B.datawisetech.corp
Description:
Live migration of ‘Virtual Machine ADFS1’ failed.

… event id 21066:
Log Name:      Microsoft-Windows-Hyper-V-VMMS-Admin
Source:        Microsoft-Windows-Hyper-V-VMMS
Date:          9/27/2018 15:36:44
Event ID:      21066
Task Category: None
Level:         Error
Keywords:
User:          SYSTEM
Computer:      NODE-B.datawisetech.corp
Description:
Failed to verify collection registry for virtual machine ‘ADFS1’: The system cannot find the file specified. (0x80070002). (Virtual Machine ID 4B5F2F6C-AEA3-4C7B-8342-E255D1D112D7).

… and event id 21024:
Log Name:      Microsoft-Windows-Hyper-V-VMMS-Admin
Source:        Microsoft-Windows-Hyper-V-VMMS
Date:          9/27/2018 15:36:44
Event ID:      21024
Task Category: None
Level:         Error
Keywords:
User:          SYSTEM
Computer:      NODE-B.datawisetech.corp
Description:
Virtual machine migration operation for ‘ADFS1’ failed at migration source ‘NODE-B’. (Virtual machine ID 4B5F2F6C-AEA3-4C7B-8342-E255D1D112D7)

Live migration fails due to non-existent SharedStoragePath or ConfigStoreRootPath explained

If you have worked with guest clusters and the ConfigStoreRootPath you know about issues with collections/ groups & checkpoints. This is related to those. If you haven’t heard anything yet read https://blog.workinghardinit.work/2018/09/10/correcting-the-permissions-on-the-folder-with-vhds-files-checkpoints-for-host-level-hyper-v-guest-cluster-backups/.

This is what a Windows Server 2016/2019 cluster that has not been configured with a looks like.

Get-VMHostCluster  -ClusterName “W2K19-LAB”

image

HKLM\Cluster\Resources\GUIDofWMIResource\Parameters there is a value called ConfigStoreRootPath which in PowerShell is know as the SharedStoragePath property.  You can also query it via

And this is what it looks like in the registry (0.Cluster and Cluster keys.) The resource ID we are looking at is the one of the Virtual Machine Cluster WMI resource.

image

If it returns a path you must verify that it exists, if not you’re in trouble with live migrations. You will also be in trouble with host level guest cluster backups or Hyper-V replicas of them. Maybe you don’t have guest cluster or use in guest backups and this is just a remnant of trying them out.

When I run it on the problematic cluster I get a path points to a folder on a CSV that doesn’t exist.

Get-VMHostCluster -ClusterName “W2K19-LAB
ClusterName SharedStoragePath
———– —————–
W2K19-LAB   C:\ClusterStorage\ReFS-01\SharedStoragePath

What happend?

Did they rename the CSV? Replace the storage array? Well as it turned out they reorganized and resized the CSVs. As they can’t shrink SAN LUNs the created new ones. They then leveraged storage live migration to move the VMs.

The old CSV’s where left in place for about 6 weeks before they were cleaned up. As this was the first time they ran Cluster Aware Updating after removing them this is the first time they hit this problem. Bingo! You probably think you’ll just change it to an existing CSV folder path or delete it. Well as it turns out, you cannot do that. You can try …

PS C:\Users\administrator1> Set-VMHostCluster -ClusterName “W2K19-LAB” -SharedStoragePath “C:\ClusterStorage\Volume1\SharedStoragePath”

Set-VMHostCluster : The operation on computer ‘W2K19-LAB’ failed: The WS-Management service cannot process the request. The WMI service or the WMI provider returned an unknown error: HRESULT 0x80070032
At line:1 char:1
+ Set-VMHostCluster -ClusterName
“W2K19-LAB” -SharedStoragePath “C:\Clu …
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo          : NotSpecified: (:) [Set-VMHostCluster], VirtualizationException
+ FullyQualifiedErrorId : OperationFailed,Microsoft.HyperV.PowerShell.Commands.SetVMHostCluster

Or try …
$path = “C:\ClusterStorage\Volume1\Hyper-V\Shared”
Get-ClusterResource “Virtual Machine Cluster WMI” | Set-ClusterParameter -Name ConfigStoreRootPath -Value $path -Create

Whatever you try, deleting, overwriting, … no joy. As it turns out you cannot change it and this is by design. A shaky design I would say. I understand the reasons because if it changes or is deleted and you have guest clusters with collection depending on what’s in there you have backup and live migration issues with the guest clusters. But if you can’t change it you also run into issues if storage changes. You dammed if you do, dammed if you don’t.

Workaround 1

What

Create a CSV with the old name and folder(s) to which the current path is pointing. That works. It could even be a very small one. As test I use done of 1GB. Not sure of that’s enough over time but if you can easily extend your CSV that’s should not pose a problem. It might actually be a good idea to have this as a best practice. Have a dedicated CSV for the SharedStoragePath. I’ll need to ask Microsoft.

How

You know how to create a CSV and a folder I guess, that’s about it.  I’ll leave it at that.

Workaround 2

What

Set the path to a new one in the registry. This could be a new path (mind you this won’t fix any problems you might already have now with existing guest clusters).

Delete the value for that current path and leave it empty. This one is only a good idea if you don’t have a need for VHD Set Guest clusters anymore. Basically, this is resetting it to the default value.

How

There are 2 ways to do this. Both cost down time. You need to bring the cluster service down on all nodes and then you don’t have your CSV’s. That means your VMs must be shut down on all nodes of the cluster

The Microsoft Support way

Well that’s what they make you do (which doesn’t mean you should just do it even without them instructing you to do so)

  1. Export your HKLM\Cluster\Resources\GUIDofWMIResource\Parameters for save keeping and restore if needed.
  2. Shut down all VMs in the cluster or even the ones residing on a CSV even if not clusterd.
  3. Stop the cluster service on all nodes (the cluster is shutdown if you do that), leave the one you are working on for last.
  4. From one node, open up the registry key
  5. Click on HKEY_LOCAL_MACHINE and then click on file, then select load hive
  6. Browse to c:\windows\cluster, and select CLUSDB
  7. Click ok, and then name it DB
  8. Expand DB, then expand Resources
  9. Select the GUID of Virtual Machine WMI
  10. Click on parameters, on (configStoreRootPath) you will find the value
  11. Double click on it, and delete it or set it to a new path on a CSV that you created already
  12. Start the cluster service
  13. Then start the cluster service from all nodes, node by node

My way

Not supported, at your own risk, big boy rules apply. I have tried and tested this a dozen times in the lab on multiple clusters and this also works.

  1. In the registry key Cluster (HKLM\Cluster\Resources\GUIDofWMIResource\Parameters) of ever cluster node delete the content of the REGZ value for configStoreRootPath, so it is empty or change it to a new path on a CSV that you created already for this purpose.
  2. If you have a cluster with a disk witness, the node who owns the disk witness also has a 0.Cluster key (HKLM\0.Cluster\Resources\GUIDofWMIResource\Parameters). Make sure you also to change the value there.
  3. When you have done this. You have to shut down all the virtual machines. You then stop the cluster service on every node. I try to work on the node owning the disk witness and shut down the cluster on that one as the final step. This is also the one where I start again the cluster again first so I can easily check that the value remains empty in both the Cluster and the 0.Cluster keys. Do note that with a file share / cloud share witness, knowing what node was shut down last can be important. See https://blog.workinghardinit.work/2017/12/11/cluster-shared-volumes-without-active-directory/. That’s why I always remember what node I’m working on and shut down last.
  4. Start up the cluster service on the other nodes one by one.
  5. This avoids having to load the registry hive but editing the registry on every node in large clusters is tedious. Sure, this can be scripted in combination with shutting down the VMs, stopping the cluster service on all nodes, changing the value and then starting the cluster services again as well as the VMs. You can control the order in which you go through the nodes in a script as well. I actually did script this but I used my method. you can find it at the bottom of this blog post.

Both methods will work and live migrations will work again. Any existing problematic guest cluster VMs in backup or live migration is food for another blog post perhaps. But you’ll have things like driving your crazy.

Some considerations

Workaround 1 is a bit of a “you got to be kidding me” solution but at least it leaves some freedom replace, rename, reorganize the other CSVs as you see fit. So perhaps having a dedicated CSV just for this purpose is not that silly. Another benefit is that this does not involve messing around in the cluster database via the registry. This is something we advise against all the time but now has become a way to get out of a pickle.

Workaround 2 speaks for its self. There is two ways to achieve this which I have shown. But a word of warning. The moment the path changes and you have some already existing VHD Set guests clusters that somehow depend on that you’ll see that backups start having issues and possibly even live migrations. But you’re toast for all your Live migrations anyway already so … well yeah, what can I do.

So, this is by design. Maybe it is but it isn’t very realistic that your stuck to a path and name that hard and that it causes this much grief or allows for people to shoot themselves in the foot. It’s not like all this documented somewhere.

Conclusion

This needs to be fixed. While I can get you out of this pickle it is a tedious operation with some risk in a production environment. It also requires down time, which is bad. On top of that it will only have a satisfying result if you don’t have any VHD Set guest clusters that rely on the old path. The mechanism behind the SharedStoragePath isn’t as robust and flexible yet as it should be when it comes to changes & dealing with failed host level guest cluster backups.

I have tested this in Windows 2019 insider preview. The issue is still there. No progress on that front. Maybe in some of the future cumulative updates, things will be fixed to make guest clustering with VHD Set a more robust and reliable solution. The fact that Microsoft relies on guest clustering to support some deployment scenarios with S2D makes this even more disappointing. It is also a reason I still run physical shared storage-based file clusters.

The problematic host level backups I can work around by leveraging in guest backups. But the path issue is unavoidable if changes are needed.

After 2 years of trouble with the framework around guest cluster backups / VHD Set, it’s time this “just works”. No one will use it when it remains this troublesome and you won’t fix this if no one uses this. The perfect catch 22 situation.

The Script

The script is below as promised. If you use this without testing in a production environment and it blows up in your face you are going to get fired and it is your fault. You can use it both to introduce as fix the issue. The action are logged in the directory where the script is run from.

Correcting the permissions on the folder with VHDS files & checkpoints for host level Hyper-V guest cluster backups

Introduction

It’s not a secret that while guest clustering with VHDSets works very well. We’ve had some struggles in regards to host level backups however. Right now I leverage Veeam Agent for Windows (VAW) to do in guest backups. The most recent versions of VAW support Windows Failover Clustering. I’d love to leverage host level backups but I was struggling to make this reliable for quite a while. As it turned out recently there are some virtual machine permission issues involved we need to fix. Both Microsoft and Veeam have published guidance on this in a KB article. We automated correcting the permissions on the folder with VHDS files & checkpoints for host level Hyper-V guest cluster backup

The KB articles

Early August Microsoft published KB article with all the tips when thins fail Errors when backing up VMs that belong to a guest cluster in Windows. Veeam also recapitulated on the needed conditions and setting to leverage guest clustering and performing host level backups. The Veeam article is Backing up Hyper-V guest cluster based on VHD set. Read these articles carefully and make sure all you need to do has been done.

For some reason another prerequisite is not mentioned in these articles. It is however discussed in ConfigStoreRootPath cluster parameter is not defined and here https://docs.microsoft.com/en-us/powershell/module/hyper-v/set-vmhostcluster?view=win10-ps You will need to set this to make proper Hyper-V collections needed for recovery checkpoints on VHD Sets. It is a very unknown setting with very little documentation.

But the big news here is fixing a permissions related issue!

The latest addition in the list of attention points is a permission issue. These permissions are not correct by default for the guest cluster VMs shared files. This leads to the hard to pin point error.

Error Event 19100 Hyper-V-VMMS 19100 ‘BackupVM’ background disk merge failed to complete: General access denied error (0x80070005). To fix this issue, the folder that holds the VHDS files and their snapshot files must be modified to give the VMMS process additional permissions. To do this, follow these steps for correcting the permissions on the folder with VHDS files & checkpoints for host level Hyper-V guest cluster backup.

Determine the GUIDS of all VMs that use the folder. To do this, start PowerShell as administrator, and then run the following command:

get-vm | fl name, id
Output example:
Name : BackupVM
Id : d3599536-222a-4d6e-bb10-a6019c3f2b9b

Name : BackupVM2
Id : a0af7903-94b4-4a2c-b3b3-16050d5f80f

For each VM GUID, assign the VMMS process full control by running the following command:
icacls <Folder with VHDS> /grant “NT VIRTUAL MACHINE\<VM GUID>”:(OI)F

Example:
icacls “c:\ClusterStorage\Volume1\SharedClusterDisk” /grant “NT VIRTUAL MACHINE\a0af7903-94b4-4a2c-b3b3-16050d5f80f2”:(OI)F
icacls “c:\ClusterStorage\Volume1\SharedClusterDisk” /grant “NT VIRTUAL MACHINE\d3599536-222a-4d6e-bb10-a6019c3f2b9b”:(OI)F

My little PowerShell script

As the above is tedious manual labor with a lot of copy pasting. This is time consuming and tedious at best. With larger guest clusters the probability of mistakes increases. To fix this we write a PowerShell script to handle this for us.

Below is an example of the output of this script. It provides some feedback on what is happening.

Correcting the permissions on the folder with VHDS files & checkpoints for host level Hyper-V guest cluster backup

Correcting the permissions on the folder with VHDS files & checkpoints for host level Hyper-V guest cluster backup

PowerShell for the win. This saves you some searching and typing and potentially making some mistakes along the way. Have fun. More testing is underway to make sure things are now predictable and stable. We’ll share our findings with you.

Frustrations about host level backups of Hyper-V guest clusters with Windows Server 2016

Introduction

With Windows Server 2016 came the hope and promise of improved backups for Hyper-V environments. And indeed Microsoft delivered on that and has given us faster, more scalable and more reliable backups. With VHD sets also came the promise of host based backups for guest clusters.

The problem is that this promise or, as it is perhaps better to be mild and careful, that expectation has not been met. Decent, robust host based backups of guest clusters in Windows Server 2016 are still not a reality. For me this means it blocked a few scenarios and we’re working on alternatives. This is a missed opportunity I think for MSFT to excel at virtualization.

The problem

Doing host based backup of guest clusters with VHD Set disks is supported in Windows Server 2016 under certain conditions.

At RTM it became clear that CSV inside the guest cluster was not supported.

You need a healthy cluster with all disks one line

These requirements are reflected in Errors discovered during backup of VHDS in guest clusters

Error code: ‘32768’. Failed to create checkpoint on collection ‘Hyper-V Collection’

Reason: We failed to query the cluster service inside the Guest VM. Check that cluster feature is installed and running.

Error code: ‘32770’. Active-active access is not supported for the shared VHDX in VM group

Reason: The VHD Set disk is used as a Cluster Shared Volume. This cannot be checkpointed

Error code: ‘32775’. More than one VM claimed to be the owner of shared VHDX in VM group ‘Hyper-V Collection’

Reason: Actually we test if the VHDS is used by exactly one owner. So having 0 owner also creates this error. The reason was that the shared drive was offline in the guest cluster

Unfortunately, this is not the only problems people are facing. Quite often the backup software doesn’t support backing up VHD Sets or when it does they fail. Some of those failings like being unable to checkpoint the VHD Set have been addressed via Windows Updates. But there are others issues.

Let’s look at the two most common ones.

Issue 1

You can make one backup an all subsequent backups fail. This is due to the avhdx files being in used and locked. This means that as long as the cluster is up and running the recovery checkpoint chain keeps growing. This can be “cleaned” or merged but only by taking down the cluster.

At the first backup live seems good.

image

The recovery checkpoint as a collection is indeed working.

clip_image003

All attempts at another backup fail.

clip_image005

Shutting down all cluster VMs and starting them up again does merge the recovery checkpoints.

Issue 2

You can make backups, successfully but the recovery checkpoints never get merged. clip_image007

This sounds “better” but it isn’t. There is no way to merge the checkpoint. Manually merging the checkpoints of a VHD Set is bad voodoo.

Both situations get you into problems and I have found no solution so far. At the time or writing I’m back at the “never ending” recovery checkpoint chain situation. But that can change back to the 1st issue I guess. Sigh.

I have found no solution so far

For now I have been unable to solve these problem. There is no fix or even a workaround. The only to get out if this stale mate is to shut down every node of the guest clusters and then restart them all. Just a restart of the guest nodes of the cluster doesn’t do the trick of releasing the checkpoints files and merging them. While this allows you to take one backup successfully again, the problem returns immediately. For you reference that was my issue with the October 2017 CU (KB)

The other scenario we run into is that the backups do work but the recovery checkpoints never ever merge. Not even when you shut down the all the guest VM cluster nodes and start them. With frequent backup that turns into a disaster of a never ending chain of recovery checkpoints. This is actually the situation I was in again after the November 2017 updates on both guests & hosts (KB4049065: Update for Windows Server 2016 for x64-based Systems and KB4048953: 2017-11 Cumulative Update for Windows Server 2016 for x64-based Systems).

To me this situation is blocking the use of guest clustering with VHD Sets where a backup is required. For many reasons we do not wish to go the route of iSCSI or vFC to the guest. That doesn’t cut it for us.

Conclusion

Host level backups of guest clusters in Windows Server 2016 are still a no go. This despite the good hopes we had with VHD Sets to address this limitation and which we were eagerly awaiting. For many of us this is a show stopper for the successful virtualization guest clusters. Every month we try again and we’re not getting anywhere. Hence the frustration and the disappointment.

More than 1 year after Windows Server 2016 RTM we still cannot do consistent host level backup a Hyper-V guest cluster, not even those without CSV, but also not those with standard clustered disks. Trust me on the fact that many of us have given this feedback to Microsoft. They know and I suggest you keep voicing your concerns to them in order to keep it on their radar screen and higher on the priority list. You can do this by opening support calls and by asking for it on user voice. Please Microsoft, we need these workloads to be first class citizens. I’m clearly not the only unhappy camper out there as noticeable in various support forums: Cannot create checkpoint when shared vhdset (.vhds) is used by VM – ‘not part of a checkpoint collection’ error and Backing up a Windows Failover Cluster with Shared vhdx?

Shared VHDX In Windows 2016: VHDS and the backing storage file

Introduction into the VHD Set

I have talked about the VHD Set with a VHDS file and a AVHDX backing storage file in Windows Server 2016 in a previous blog post A first look at shared virtual disks in Windows Server 2016. One of the questions I saw pass by a couple of times is whether this is still a “normal VHDX” or a new type of virtual disk. Well the VHDS files is northing but a small file containing some metadata to coordinate disk actions amongst the guest cluster nodes accessing the shared virtual disk. The avhdx file associated with that VHDS file is an automatically managed dynamically expanding or fixed virtual disk. How do I know this? Well I tested it.

There is nothing that preventing you from copying or moving the avhdx file of a VHD Set that not in use. You can rename the extension from avhdx to vhdx. You can attach it to another VM or mount it in the host and get to the data. In essence this is a vhdx file. The “a” in avhdx stands for automatic. The meaning of this is that an vhdx is under control of the hypervisor and you’re not supposed to be manipulating it but let the hypervisor handle this for you. But as you can see for yourself if you try the above you can get to the data if that’s the only option left. Normally you should just leave it alone. It does however serve as proof that the VHD Set uses an standard virtuak disk (VHDX) file.

I’ll demonstrate this with an example below.

Fun with a backing storage file in a VHD Set

Shut down all the nodes of the guest cluster so that the VHD Set files are not in use. We then rename the virtual disk’s extension avhdx to vhdx.

image

You can then mount it on the host.

image

And after mounting the VHDX we can see the content of the virtual disk we put there when it was a CSV in that guest cluster.

image

We add some files while this vhdx is mounted on the host

image

Rename the virtual disk back to a avhdx extension.

image

We boot the nodes of the guest cluster and have a look at the data on the CSV. Bingo!

image

I’m NOT advocating you do this as a standard operation procedure. This is a demo to show you that the backing storage files are normal VHDX files that are managed by the hypervisor and as such get the avhdx extension (automatic vhdx) to indicate that you should not manipulate it under normal circumstances. But in a pinch, it a normal virtual disk so you can get to it with all options and tools at your disposal if needed.