Set the preferred site for a CSV in a site-aware stretched failover cluster


I have presented many time over the past tears on the new and enhanced capabilities of Microsoft Failover Clustering in Windows Server 2016 (Experts Live, Cloud & Datacenter Conference Germany, MicroWarehouse’s Windows Server 2016 Launch Event etc.) Feedback has shown me that there is still a lot of need for good failover cluster design and implementation guidance.

One area of enhancement is that you now have site-aware failover clusters in Windows Server 2016. That helps optimize the, availability, behavior and performance of the workload. It leveraged cluster fault domains and in this case those fault domains are the sites where the cluster nodes reside.


Set the preferred site for a CSV in a site-aware stretched failover cluster

You can leverage the site awareness to do all kind of configuration optimizations. You can set a preferred site creating a primary and a DRC site. The cluster behavior will optimize for that scenario. It will also help with situation like quorum split more easily and elegantly. You can create an “Active-Active” site configuration because a cluster groups, such as virtual machines can have their own preferred site.

As you can see in the picture above there is a thing called Storage Affinity. That means that VMs follow storage and are placed in same site where their associated storage resides. As such VMs will begin live migrating to the same site as their associated CSV after 1 minute. The CSV load balancer will distribute within the preferred site. That’s cool. But when setting a preferred site at the cluster group level like for virtual machines, how does one do this for a CSV?

It’s actually quite simple. A CSV is a cluster group, just like a VM is. So, for every CSV you can set that preferred site. You just grab the cluster group a bit differently. Let’s look at an example.

For a VM you’d do this: (Get-ClusterGroup -Name DidierTest01).PreferredSite = ‘Dublin’

Now for a CSV we go about it as follows:

Get-ClusterSharedVolume “Cluster Disk 1” | Get-ClusterGroup | Fl *


The preferred site has not been set yet. To set the preferred site for a CSV you can do the following:

$NTFS01 = Get-ClusterSharedVolume “Cluster Disk 1” | Get-ClusterGroup $NTFS01.PreferredSite = “Dublin” $NTFS01.PreferredSite


You can remove a preferred site by setting it to $Null:

$NTFS01.PreferredSite = $Null

That was not to hard was it? There is one other thing to keep in mind. Do not forget to set up your site fault domains first and set the site for your cluster nodes before you start configuring preferred sites at the cluster group level or it will throw an error. That’s the minimal setup of a site-aware cluster you need to have in place before you can do more fine-grained configurations.

New-ClusterFaultDomain –Name Dublin –Type Site –Description “Primary” –Location “Dublin DC1”
New-ClusterFaultDomain –Name Cork –Type Site –Description “Secondary” –Location “Cork DC2″
Set-ClusterFaultDomain –Name Node-A –Parent Dublin
Set-ClusterFaultDomain –Name Node-B –Parent Dublin
Set-ClusterFaultDomain –Name Node-C –Parent Cork
Set-ClusterFaultDomain –Name Node-D –Parent Cork


If you don’t do this and try to set preferred sites at the cluster group level you’ll get an error like:

Exception setting “PreferredSite”: “Unable to save property changes for ‘e95ad724-97d3-4848-91db-198ab8312737’.
The parameter is incorrect”
At line:1 char:1
+ $NTFS01.PreferredSite = “Dublin”
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], SetValueInvocationException
+ FullyQualifiedErrorId : ExceptionWhenSetting

There is a lot more to say about site-aware stretched clusters but how to deal with setting a preferred site for a CSV must be the most common question I get on this subject. Well, now it’s published to help you all out. I hope it helps.

In-place upgrade of an Azure virtual machine


In the cloud it’s all about economies of scale, automation, wipe and (redeploy). Servers are cattle to be destroyed and rebuild when needed. And “needed” here is not like in the past. It has become the default way. But not every one or every workload can achieve that operational level.

There are use cases where I do use in place upgrades for my own infrastructure or for very well known environments where I know the history and health of the services. An example of this is my blog virtual machine. Currently that is running on Azure IAAS, Windows Server 2016, WordPress 4.9.1, MySQL 5.7.20, PHP. It has never been reinstalled.

I upgraded my WordPress versions many times for both small incremental as major releases. I did the same for my MySQL instance used for my blog. The same goes for PHP etc. The principal here is the same. Avoid risk of tech debt, security risks and major maintenance outages by maintaining a modern platform that is patched and up to date. That’s the basis of a well running and secure environment.

In-place upgrade of an Azure virtual machine

In this approach updating the operating system needs to be done as well so my blog went from Windows Server 2012 R2 to Windows Server 2016. That was also an in place upgrade. The normal way of doing in place upgrades, from inside the virtual machine is actually not supported by Azure and you can shoot yourself in the foot by doing so.

The reason for this is the risk. You do not have console access to an Azure IAAS virtual machine. This means that when things go wrong you cannot fix it. You will have to resort to restoring a backup or other means of disaster recovery. There is also no quick way of applying a checkpoint to the VM to return to a well known situation. Even when all goes well you might lose RDP access (didn’t have it happen yet). But even if all goes well and that normally is the case, you’ll be stuck at the normal OOBE screen where you need to accept the license terms that you get after and upgrade to Windows Server 2016.


The default upgrade will boot to that screen and you cannot confirm it as you have no console access. If you have boot diagnostics enabled for the VM you can see the screen but you cannot get console access. Bummer. So what can you do?

Supported way of doing an in-place upgrade of an Azure virtual machine

Microsoft gives you two supported options to upgrade an Azure IAAS virtual machine in

An in-place system upgrade is not supported on Windows-based Azure VMs. These approaches mitigate the risk. The first is actually a migration to a new virtual machine. The second one is doing the upgrade locally on the VHD disk you download from Azure and then upload to create a new IAAS virtual machine. All this avoids messing up the original virtual machine and VHD.

Unsupported way of doing an in-place upgrade of an Azure virtual machine

There is one  way to do it, but if it goes wrong you’ll have to consider the VM as lost. I have tested this approach in a restored backup of the real virtual machine to confirm it works. But, it’s not supported and you assume all risks when you try this.

Mount your Windows Server 2016 ISO in the Windows Server 2012 R2 IAAS virtual machine. Open an administrative command prompt and navigate to the drive letter (mine was ESmile of the mounted ISO. From there you launch the upgrade as follows:

E:\setup.exe /auto upgrade /DynamicUpdate enable /pkey CB7KF-BWN84-R7R2Y-793K2-8XDDG /showoobe none

The key is the client KMS key so it can activate and the /showoobe none parameter is where the “magic” is at. This will let you manually navigate through the wizard and the upgrade process will look very familiar (and manual). But the big thing here is that you told the upgrade not to show the OOBE screen where you accept the license terms and as such you won’t get stuck there. So fare I have done this about 5 times and I have never lost RDP access due to the in-place upgrade. So this worked for me. But whatever you do, make sure you have a backup, a  way out, ideally multiple ways out!

Note that you can use  /Quiet to automate things completely. See  Windows Setup Command-Line Options

Nested virtualization can give us console access

Since we now have nested virtualization you have an option to fix a broken in-^lace upgrade but by getting console access to a nested VM using the VHD of the VM which upgrade failed. See:


If Microsoft would give us virtual machine console access or  DRAC or ILO capabilities that would take care of this issue. Having said all that, I known that in place upgrades of applications, services or operating systems isn’t the cloud way. I also realize that dogmatic purism doesn’t help in a lot of scenarios so if I can help people leverage Azure even when they have “pre cloud” needs, I will as long as it doesn’t expose them to unmanaged risk. So while I don’t recommend this, you can try it if that’s the only option you have available for your situation. Make sure you have a way out.

IAAS has progressed a tremendous amount over the last couple of years. It still has to get on par with capabilities we have not only become accustomed to but learned to appreciate over over the years. But it’s moving in the right direction making it a valid choice for more use cases. As always when doing cloud, don’t do copy paste, but seek the best way to handle your needs.

Hyper V Amigos Showcast 15 – VMFleet explained

After a short break in broadcasts, due to extremely busy times, the Hyper-V Amigos ride again! Yes, fellow Microsoft MVP Carsten Rachfahl (@hypervserver) from Rachfahl IT Solutions and yours truly are back in the saddle!

In episode 15 of the Hyper-V Amigos Showcast we look at VMFleet. VMFleet is a free Microsoft test suite to show/test and help analyze the performance of a Hyper-converged Storage Spaces Direct Setup.


In this episode Hyper V Amigos Showcast 15 – VMFleet explained we show you how to set it up, how it works and how to measure and evaluate your S2D deployment with it. We also share some real life tips with you. All this in just around 2 hours. So stick around for the long haul!

Cluster Shared Volumes without Active Directory


Cluster Shared Volumes without Active Directory will come online if certain conditions are met. Basically, when the cluster can form. That’s what we’ll talk about here. There are a lot of things to consider when virtualizing your Active Directory environment, partially or completely. Too much for this blog post alone and much of it has been discussed before. Here I’ll discuss when people count on their Cluster Shared Volumes coming online when active directory is not available but are disappointed and think that it’s a bug or a broken promise. It is not! We know that since Windows Server 2012 the CSVs coming online do not depend on Active Directory being available (thanks to the local CLIUSR account being used for cluster starts).

Cluster Shared Volumes without Active Directory

So, let’s address getting your Cluster Shared Volumes online when AD is not available. The things to realize is that not having Active Directory has been taken care off. The thing that still can go wrong is that the cluster doesn’t come on line properly and that means that the CSV LUNs won’t be online as those are cluster resource. Hyper-V can boot the VMs without the cluster being formed but as the VMs reside on a CSV and those are not available, that’s what’s causing the problem. That means that getting your cluster to come up is the real issue.

Getting your cluster to come up is the real issue.

If cluster shared volumes can come up without a domain controller / AD being available since Windows Server 2012 (Failover Clustering and Active Directory Integration) how is it that some many people still have issues with it? How do you make this work for you? You can use a disk witness to protect you in most cases. When you have a file share or cloud witness you can take some step to avoid running into this issue.

There is a great article on cluster behavior here: Failover Cluster Node Startup Order in Windows Server 2012 R2 (the same rules apply for Windows Server 2016). Read it and you’ll notice that the behavior differs depending on whether you have a witness defined and whether that witness is a witness disk or a file share or cloud witness. The disk witness has a copy of the cluster database and if available will help you out of any situation where the paxos on the disk witness (if it’s available) is more recent then the one on the cluster node as the node will download the cluster database info from the disk witness. But a file share or cloud witness don’t have a copy, so they have a small disadvantage under certain scenarios. CSV’s that won’t come up is when booting the nodes in the wrong order when using a file share or cloud witness is one of those scenarios but not having AD isn’t the root cause of this.

Some people will never notice this issue at all, especially not when they have disk witness, but when they do, it might be at a very inconvenient moment in time. Examples of where this situation can occur are a single cluster environment where the domain controllers are running on CSV and high available in that cluster that was shut down completely, the cluster has a file share witness and the nodes are started in the wrong order.

Making sure your CSVs come online = clustering being formed

Well for one make sure you are using Windows Server 2012 or higher for your cluster. That’s a given.

Beyond that you basically just need to know what to do in what scenario to get your cluster up and running so you won’t have issues with getting the CSV to come up. You just have to follow some rules of thumb and you’ll be fine. Also, there’s almost always a way to get out of pickle, just don’t panic. But also remember that you can make your live easier when you design your solutions with failure in mind and by knowing your options so you can act correctly. I my example I’ll be using Hyper-V cluster with CSVs but the same goes for SOFS, SQL Server clusters leveraging CSVs etc.

Planned down time

If you’re shutting down a complete cluster you have two options to make sure things go a smooth as possible.

Option 1 – A clean cluster shutdown by the book

  • Shut down the workload, i.e. the VMs.
  • Stop the cluster
  • Shutdown the Cluster nodes.
  • Boot the cluster nodes. You can start with any you like. The CSVs will come on line. You will be able to start the VMs. Do start with the domain controllers and wait for them to come on line before starting the others.

During this you’ll see some “collateral” events, errors, warnings due to Active Directory not being available. The cluster name has issues without Active Directory but that a management connection point, it doesn’t mean the cluster doesn’t work. Once Active Directory is available the cluster name will come on line automatically when the default failure policy restarts it. You can also manage the cluster via RDP or console by connection to “.” locally on that node or use the running node name. You can also try to bring cluster name on line manually when Active Directory is up and running.

Option 2 – A clean cluster shutdown as it happens most of the times in real life

Which is one a lot of people do to keep part of the work load running as long as possible.

  • Shut down the no critical workload, i.e. the VMs.
  • Pause a node so the critical workloads live migrate to other nodes
  • When the node is paused, shut down the node.
  • You rinse and repeat this until the last node is left with only the most critical VMs


  • Finally, you stop the workload on that last cluster node and shut it down as well.
  • Now comes the critical part: Remember what node you shut down last. You have to start that one first and you’ll see that your CSV will come on line. If you boot another node, you might panic as the CSV will not come on line.

Now I need to correct this a little bit. With a disk witness you are OK whatever node you boot. When the paxos numbers on the first node to boot and the disk witness are compared the most recent copy will be used. Either the local one on the node will be used directly or after it has been updated with the data form the disk witness. To make things simple for the ops team I always tell them to note the last node they shut down anyway no matter what type of witness they have. It’s good info to have.

With a file share or cloud witness the shutdown/startup order really comes into play. The reason this happens is that by shutting down node by node we end up with a one node cluster (last man standing).  When that’s shut down that’s the only node that knows about the last (potential) changes in the cluster as it holds a copy of the cluster database. Remember that a files hare or a cloud witness has no copy of the cluster database. That’s why the last node to be shut down has to come on line first when comparing the paxos numbers with the witness as that node can form a cluster. If the node that boots first does not hold the most recent paxos number it cannot download the cluster databases info from the file share or cloud witness. Such a node cannot form a cluster and bring the CSVs online. If the first node to boot was the last one to shut down, it can form a cluster and the CSVs will come on line. This is the big difference with option one where you shut down the entire cluster and then take the nodes of line.

You might not know or remember the order. If that’s the case you still have options like starting the cluster node with the -fixquorum option (net.exe start clussvc /forcequorum) at the risk of loosing some cluster changes that are not in the local cluster database.

No need to go to immediately backups, extract the domain controller VMs from SAN snapshots or mount a LUN to a different machine to extract the VM files for the DC or so. Don’t panic!

One or more failed nodes

Well as long as the cluster survives your domain controller VMs should fail over. Keep ‘m on separate node (anti-affinity), separate CSV LUNs, if possible separate clusters if all domain controller virtual machines are going to be running high available on a cluster node and that cluster is still functional after all. No issues here.

Total cluster failure

The cluster nodes all show due to a “global” BSOD or are turned off due to a power failure or a storage array crash. This is more the realm of bad dreams I know, it does happen. Often things will recover and you’ll be fine but you can do your part. The same rules apply, get the cluster to form and you’ll have your CSVs on line. In a bad case -fixquorum is your friend but normally it’s not your first option. In the worst case you’ll need recovery from backup of the cluster or rebuild it. It’s a very bad day if it comes to that. And cluster recovery is not the subject of this post.


Don’t blame Active Directory and start troubleshooting or fixing the wrong problem. So yes, CSV will come on line when certain conditions are met and you can work yourself out of a pickle if needed. But during a disaster that’s only extra work and stress you might not want to worry about if you can avoid it. It’s good to know how to resolve issues around CSVs not coming online when the shit hits the fan as even the best laid out plans tend to get side tracked by reality when disaster strikes.

If you cannot guarantee control over all the prerequisites and might not have the skills in please when needed, you might consider other options. Some of these are actually the best practices of the past when a CSV would indeed not come on line without active directory in any way. This is great for AD related issues but not for you offline CSVs, they need the cluster to form properly!

Sure, you can run the domain controller virtual machines on local storage, and not made high available. This cloud be on one of the cluster nodes (*) or on a stand-alone Hyper-V host. Having a physical domain controller is also a possibility. This helps avoid issues with AD in virtualized environments as many other services are very dependent on them and it’s good to have on one available all of the time and get them back on line a.s.a.p..

I’ll leave you with the fact that virtualizing domain controllers can be done but it pays to study up on how to do it well and test your assumptions in the lab. There is a lot of information on virtualizing domain controllers for a reason. Read it and process what you’ve learned from it. You might find that this CCV thingies is not the most complex subject to deal with.

(*) Please note that some cluster deployments like HCI based on S2D do not support running other (local) storage in addition to the boot OS and the S2D storage pool volumes.