Azure Stack HCI details

Microsoft has announced a successor of the current Azure Stack HCI. The current solution is based on Windows Server 2019 using Hyper-V and Storage Spaces Direct. The new Azure Stack HCI solution is based on a new operating system originating from Windows Server 2019, called Azure Stack HCI. 

On our dedicated Azure Stack HCI page, we have explained what the solution is all about. In this blog, we’re diving a little deeper in the details.

Azure Stack HCI Operating System 

Azure Stack HCI is not only the name of the solution, but also the name of the Operating System. That means that Azure Stack HCI OS is breaking loose from Windows Server, and the (slow paced) release cadence. The Azure Stack HCI OS will be updates much more frequently like the SAC releases providing new features or improvements at a faster rate. 

As Azure Stack HCI is released before the upcoming version of Windows Server, we also get the announced enhancements sooner as expected. Such as;  

Full stack automatic updates

Firmware and drives updated through integration with Windows Admin Center. Automatic, no manual intervention needed.
See this screenshot from EMC Dell for the visuals, or take a look at their 7-min video here.

Storage rebuilds 75% faster

Azure Stack HCI includes a completely renewed Storage Spaces Direct repair mechanism! The cluster now tracks the changes in the data at a much finer granularity. This improves rebuild times up to 75%, narrowing maintenance windows further. 

Stretched clusters

Azure Stack HCI also provides us with the Stretched Clustering feature, build on top of Storage Replica. Using this new feature, we can span an Azure Stack HCI cluster over multiple sites providing business continuity and disaster recovery (BCDR) capabilities. 
Azure Stack HCI supports synchronous and A-synchronous replication. 

Affinity and Anti-Affinity

With the release of Azure Stack HCI there is a new feature included called ‘VM Affinity and Anti Affinity’.  


With Affinity rules you can achieve binding of two or more resources together. For example, you want your front-end webservers and back-end databases servers on the same physical location to avoid latency and increase performance. 


With Anti-Affinity, we achieve the exact opposite. 
If we want to distribute front-end webservers over multiple physical locations (fault domains) we can use Anti-Affinity rules. 
When one physical location is offline due to maintenance or unexpected failure, you make sure your application stays online. 

Windows Admin Center

With the release of Azure Stack HCI Microsoft also heavily invested again in Windows Admin Center. Windows Admin Center now includes cluster create options and with that several workflows to created different types of clusters like HCI, HCI+SDN and more.  
With these workflows we can setup the cluster completely using Windows Admin Center. Automation in the background makes sure the asked components are installed according to best-practices. 

Stripped down OS

Because Azure Stack HCI is intended for HCI clusters only, the OS it will be stripped down from unnecessary features. Meaning, many features that are currently part of the Window Server OS will not be available in the Azure Stack HCI OS… 
Current features and roles in Windows Server 2019: 268 
Current features and roles in Azure Stack HCI: 193 
For example, the Active Directory and related roles such as DNS, Certificate Services, Federation Services, DHCP and Print Services will not be included, and more features might follow.  
These features will still be available in the regular Window Server releases, just not in Azure Stack HCI.  

Azure Stack HCI Billing

Since Azure Stack HCI is a cloud solution, the billing model will change to a cloud billing model.

Traditional Windows Server licensing

With Windows Server there always has been a licensing model calculated per physical processor core. Depending on the number of physical processor cores in your server, a number of core-packs must be purchased.

Azure Stack HCI licensing

With Azure Stack HCI you are also licensed per physical processor core. The difference with Windows Server licensing is that there is no concept of core-packs, you pay for the amount of physical processor cores in your cluster.

With this model the licensing costs switches from a CAPEX to an OPEX model.
When Azure Stack HCI is down or up-scaled the day-to-day expenses change.

Because the billing is managed through Microsoft Azure we can leverage the tools available to get more insights on costs. For example, with Azure Cost Analyses we can query the information and provide forecasts. In addition, the Azure APIs can be used with third party tooling for cost management.

Guest operating systems not included

One important aspect to note is that guest operating systems are not included in the license, like with Windows Server 2019 Datacenter edition.
This means that you will need to license VMs running on the Azure Stack HCI solution.

Azure Connection required once per month

Because the billing runs through Microsoft Azure, the cluster must be registered to Microsoft Azure within 30 days after deployment. After registration the cluster needs to connect to Microsoft Azure once every 30 days to report cluster status. If the cluster is unable to report the cluster will be out of policy.


Support via Azure support tickets

As cloud solution, the support of Azure Stack HCI falls under the umbrella of Microsoft Azure support. That means that you could request support by going to and file a support request there for your Azure Stack HCI solution.


Azure Stack HCI resource provider

Microsoft has created a dedicated resource type in Azure Resource Manager for Azure Stack HCI clusters.

By registering Azure Stack HCI clusters to the resource provider in Microsoft Azure an Azure Resource is created that represents the cluster.


Self-service VMs through Azure Portal

Want to offer your users a consistent experience with Azure? You now can.
Azure Stack HCI makes use of the same toolset as Microsoft Azure, including the portal and ARM templates. Using Azure Resource Manager (ARM) you can also delegate access to users in your Azure AD.

Contact Splitbrain for more information

Unsure how the new Azure Stack HCI fits in your organization? Or what is going to happen to your existing Azure Stack HCI clusters based on Windows Server 2019?

Contact us, we’re happy to help you.

    Automatically Update Storage Spaces Direct (S2D) Clusters

    Windows Updates may seem as ordinary business or something that you will deal with when the time is there, bear with us for a moment to explain why automatic updates on Storage Spaces Direct are different.

    For a long time now, we all know that it’s important to update our servers regularly with the latest Windows Updates for several reasons. 

    • It improves security because all software contains security flaws. Those flaws can be exploited for the wrong reasons by the wrong people. The updates fix the known security issues.

    • In some cases, it may improve performance because after all data from the field may give insights and some bits or bytes were not working as efficient as planned.

    • The stability of your environment may also increase. Since bugs are reported and get fixed and released through Windows Updates.

    Not your regular set of servers

    There are lots of ways to update your servers. You could do nothing, and Windows Update will at some point install the updates and eventually reboot your server. You could use Group Policies to download updates from Microsoft and schedule installation and reboot times to fit the company update policy. Other tools like Windows Server Update Service (WSUS) with GPO’s, System Center Configuration Manager (SCCM), Azure Update Management, or other third-party tools can also help to update your servers in a more controlled, centralized, and efficient way. When we look at clusters, in this case specifically Hyperconverged Infrastructure clusters, most of these tools are not sufficient enough and you should avoid using them. These HCI servers are not your regular set of servers, they require special attention and procedures to update them.


    Not very time-efficient but you can do it manually. Before you start, first validate the cluster status is healthy, then put a node in maintenance mode, install updates, restart the node. When it’s back online, monitor and wait for the storage to synchronize. When done, you can resume the node in the cluster. Now you can continue with the second node and repeat the process for every node in the cluster. Updating one node and waiting for the storage synchronization could take anywhere between 10 minutes and several hours depending on the change rate and performance of the nodes. You can imagine that this can take up several nights or weekends of IT personnel that could be spent otherwise.

    Virtual Machine Manager

    System Center Virtual Machine Manager (SCVMM) can help with automatically updating your S2D clusters by automating the update procedure. This way IT personnel can use their time on other matters and human errors is brought to the minimum. Virtual Machine Manager has specific support for Storage Spaces Direct or Azure Stack HCI clusters and takes care of the updating, restarting, and monitoring the storage repair jobs for you. You only need to start it, sit back, and let Virtual Machine Manager take care of the rest.

    Cluster Aware Updating

    Where SCVMM is additional software you need to purchase or may already have purchased, Cluster Aware Updating (CAU) is a free tool embedded in every Windows System as a feature. CAU is also capable of dealing with S2D or Azure Stack HCI clusters. Just like VMM, CAU also automates the update procedures and is aware of storage synchronization jobs.
    Three benefits of using Cluster Aware Updating;

    1. CUA allows update scheduling to install updates on a specific day and time

    2. Ability to use pre/post scripts to perform custom (Powershell) actions before or after an update of a node.

    3. CUA is able to install drivers and firmware in the process.

    Azure Automation

    Azure Update Management is a new way of automating Windows Updates on your servers. These servers can run in Azure or in your own datacenter. As it is a cloud offer on Azure, Microsoft is heavily investing in this. But still today you should avoid Azure Automation Update Management to patch cluster nodes. As described earlier this tool is not aware of clustering or storage jobs and will threaten your nodes as single instances, and things can miserably wrong fast.

    VMM or CUA?

    That leaves us with two choices. VMM and CAU both have their pro’s and con’s, but they have one thing in common.. they both save you time.
    If you want to learn more about updating your Storage Spaces Direct or Azure Stack HCI cluster and the different tools that are available to use you could watch the “Automatically Update S2D Cluster” video (in Dutch for now). In about 20 minutes we talk in-depth about the different tools to update Storage Spaces Direct or Azure Stack HCI clusters and go through the pros and cons. We will demonstrate both update processes and tell you all you need to know! Access the video here!

    Free 20-minutes video on Automatically update Storage Spaces Direct Clusters (Dutch)

    How to get your file server in Azure

    In today’s cloud orientated world, lots of File Servers lose the battle to modern solutions like Teams and Sharepoint. But what if these solutions don’t work for your company. For example, these files are not supported on those platforms or the applications working with the files don’t support accessing it from any other type of share than CIFS or SMB. Files are too big and accessed to regularly which cause latency or a too big demand on the internet connection?

    Are you out of luck and cannot take advantage of cloud services for this? Maybe not yet.. Typically, for most of the organizations 80% of the data is never to almost never accessed. What if the clients and applications require that the hot data is available with low latency? We can use Azure File Sync to move the 80% of cold data to Azure Files. This way we save disk space on storage. If all the files are stored in Azure it is also possible to store them in Azure Backup! It is most likely cheaper and automatically offsite.

    Let’s look at Azure Files and Azure File Sync!

    What is Azure Files?

    With Azure Files you have the ability to store files in Azure Storage accounts which can be presented as files shares that you can access over SMB. Microsoft put in a lot of effort the past year to enable NTFS permissions on this, and they have done a pretty good job in making it more usable now. They enabled AD integration so you can use NTFS permissions and groups now. And you can access the shares from remote offices and your datacenters with Azure Private Link. And last but not least? you can also use DFS-N (Distributed File Service Namespace) now.

    At Splitbrain we always recommend the use of DFS-N in file servers. DFS-N gives you great flexibility in case of migrations or when you need to move files and folders around to other disks or servers.

    What resources do we need?

    You can use different storage accounts based on your needs. For example in the case of availability you can use Local Redundant Storage (LRS), Zone Redundant Storage (ZRS) or go global with Global Redundant Storage (GRS). And there is a performance point of view with regular or premium storage.


    In Azure you pay for the resources you use. For Azure Files you can take a look at Azure Files pricing overview to calculate how much it will cost if you migrate your files to Azure Files. Keep in mind that not only storing the files in the share cost money. With accessing, listing and changing the files you will also be charged based on x amount of actions. In addition downloading the files from Azure Files to the client are charged as described here.

    What is Azure File Sync?

    With Azure File Sync you can extend your current file server to Azure in a tiered storage principle. You use your current file server as endpoint for your clients with all the current features there are today and offload the bulk of your data to Azure. You can configure the Azure File Sync agent to keep files newer than x amount of days on the file server per share or choose to not tier at all. This way most of the hot data is locally and only changes are sync from and to Azure.

    With Azure Files, Azure File Sync and your file server you can have best of both worlds!

    Note that you cannot use DFS-R and AFS Tiering on the same volume, they will bite each other.

    What resources do we need?

    With Azure File Sync we also require storage accounts to store the data. The same rules apply for the different types of storage accounts as described in the chapter Azure Files. On top of that we need a storage sync service to takes care of the synchronization and access of the data from the file server.


    For Azure Files information you can view the pricing chapter for Azure Files above. On top of that we also need an Azure File Sync Service (or storage sync service) and that one is free if you only use one file server. When you have more you will be charged for the additional servers. Keep in mind that most of your data that is changing is on your file server. So your operational costs will be lower with Azure File Sync in compare to Azure Files.

    Now let’s dive into that!

    Azure Files and Azure File Sync use cases

    To give you a better understanding of the possibilities with Azure Files and Azure File Sync we describe some example scenario’s below.

    Azure Files

    In this use-case the company moves all the files to Azure Files. Most of the companies keep the SMB port (445) closed to the internet. In addition, there are several ISPs that block SMB on their networks. To be able to move and access the files from the datacenter and/or office locations, we first need to setup a Site-to-Site VPN or an ExpressRoute. We also need our ADDS (Active Directory Domain Services) synced to AAD (Azure Active Directory) and enable ADDS authentication on the storage account for the file shares. The setup requires an Azure Private Link and Azure Private DNS to be able to resolve and access the Azure files shares over the ExpressRoute or VPN.

    If your company is already using several resources in Azure and you already have an ExpressRoute or VPN connection you can leverage this.

    We also need a Domain controller and DNS server in our datacenter/office and a server to host our DFS namespace. When we put all that in the mix and configure it the right way your users are able to access the file shares running in Azure.

    User A accesses the DFS Share and browse the Marketing folder. When opening the file, it is downloaded from the storage account to his device and opened.

    This scenario is great for small deployments, but this can get problematic for a number of reasons. For example when you have lots of users accessing the files. The files might be too large. These examples would have impact on the available internet bandwidth and could lead to other issues in the organization. The added latency could become a problem for some applications and the application experience becomes slow. If the internet connection is gone, so are the files. And there are more of these technical challenges to tackle when your environment is getting bigger. For these reasons Azure Files might not be the solution for your organization.

    Single file server with Azure File Sync

    We have a single file server running in your datacenter with for example 10 terabytes of storage. That takes up a lot of data on the underlying storage system and the backup.

    For this setup we need very little configuration in Azure. An Azure subscription with a storage account and Azure File Sync Service is all that we need. In the scenario described above all clients connect directly over SMB to the storage account. In this setup all users use SMB to connect to the file server and if a file is not local, the agent pulls the parts of the file that are needed over SSL to the server. If DFS-N is in the mix, it is also easy to migrate to new smaller disks while uploading the data to Azure to save space on your file server and storage. You can enable deduplication to further lower the storage footprint. Beware that files are unduplicated when they land in the storage account, so we cannot save space there.

    In this scenario user A accesses files from the IT folder in the DFS Share that are stored on the file server and delivered from local cache. The other file is from the marketing folder and not locally. The agent pulls the first bits to open the file to improve load time for the user while it continues to download the remaining bits. This way, Azure File Sync gives a performance advantage over the first scenario with Azure Files when working with big PDFs, PowerPoints or word documents when tiered files need to be downloaded from Azure Files.

    If your company is already using several resources in Azure and you might have an ExpressRoute connection, you can take advantage of syncing over Express Route instead of over the internet and use private endpoints to further lock down access.

    File server cluster with Azure File Sync

    In some cases, a company is more dependent on the files being available at all times and have an highly available (HA) file server. If you require an HA file server and currently have a cluster? No problem! The Azure File Sync agent is cluster aware. All we need is a second agent added to the scenario above with the single server. This way we can offload the data in the file server cluster to Azure File Shares.

    Multiple sites and regions use cases

    Most of the Azure resources and that include Azure Files are bound to their region for various reasons. For example underlying infrastructure reasons like network latency between resources. If your company operates on more geographical locations, it might not work to centralize files to a single place or a single region for Azure Files. In order to use multiple regions we need additional resources in the second region. US users accessing their files in Europe is less efficient because of the large distance. We can use Azure Files and Azure File Sync to offload data to Azure to overcome these challenges.

    Multi region with Azure Files

    In the example below we have offices in Europe and the US. The users can access their files through their locally available DFS Namespace and even access files from other locations. All files are pulled from Azure files to the user device for accessing and editing.

    Based on the setup, cross region traffic flows might be different. In the above example User C access a file in the Marketing US folder that is close to his office. User D access a file from the IT EU folder. The file from the Europe region is downloaded to his device and opened. Like in the first scenario all files come directly from the internet.

    Multi region with Azure File Sync

    As described in the scenario above with Azure Files, the setup with multiple locations is also possible with Azure File Sync. Users in both locations can access the files from their local file server and if the files are not available locally, the Azure File Sync agents pulls the bits from Azure Files transparently. When accessing files in the other region, like User C does, the same rules apply. If the file is locally available on the Europe file server, it’s presented directly to the user. If the file is not locally available, the agent of the file server in that region downloads the bits and provides it to the user so the file can be accessed.

    Move to Azure IaaS with Azure File Sync

    In some cases, companies move their file server to Azure IaaS. While the concept “Lift and Shift” looks plain and simple for file servers, it might not always be the answer because of disk efficiency, size and layout. Moving your file server 1-on-1 without optimizing it with cloud services can become a very cost inefficient solution. We have worked at projects with file servers containing 15TB of storage costing well over $2000 per month. When we optimized the fileserver with Azure File Sync, the costs dropped with more than 50%. The more storage, the bigger the savings.

    Pro-tip: Azure Backup

    Azure Backup is an Hybrid Backup solution on Microsoft Azure. With Azure Backup you are able to backup your VMs, SQL workloads and Files from your datacenter or hybrid datacenter. When using Azure Files and Azure File Sync you could leverage Azure Backup to further reduce datacenter storage costs and take advantage of the native integration of Azure Backup in Azure Files.

    In the case of Azure Files you may no longer have the option to backup the files in your datacenter. Well you technically could, it is probably not very efficient… With Azure Files sync you could do a file level backup of your file server but that would initiate a download of all the files and we don’t want that to happen.

    When going forward with a hybrid datacenter and moving files to the cloud, its important to also include the backup strategy in your design. When using Azure files it could be more cost efficient to use Azure Backup instead of you current backup solution.


    To wrap things up, we go back to our initial question. Can you still move files to the cloud if you can’t use Teams or SharePoint.. Yes you can!

    If you are looking at lowering the storage footprint or postpone a storage investment the above described scenarios might benefit you greatly. Start thinking about what an hybrid datacenter could do for you.

    Although it might seem straightforward, setups like this can be quite complicated and specific features might not work as you expect, backup is not as simple now and DR brings new options to the table. Based on the design there could also be hidden costs that are not as obvious as plain storage and/or license costs? At Splitbrain were a happy to help you out if you are looking at a hybrid datacenter with Azure Files and/or Azure File Sync, just drop us an e-mail!

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