Deploying a Highly Available File Server in Azure IaaS (ARM) with SIOS DataKeeper

In this post we will detail the specific steps required to deploy a 2-node File Server Failover Cluster in a single region of Azure using Azure Resource Manager. I will assume you are familiar with basic Azure concepts as well as basic Failover Cluster concepts and will focus this article on what is unique about deploying a File Server Failover Cluster in Azure.

With DataKeeper Cluster Edition you are able to take the locally attached storage, whether it is Premium or Standard Disks, and replicate those disks either synchronously, asynchronously or a mix or both, between two or more cluster nodes. In addition, a DataKeeper Volume resource is registered in Windows Server Failover Clustering which takes the place of a Physical Disk resource. Instead of controlling SCSI-3 reservations like a Physical Disk Resource, the DataKeeper Volume controls the mirror direction, ensuring the active node is always the source of the mirror. As far as Failover Clustering is concerned, it looks, feels and smells like a Physical Disk and is used the same way Physical Disk Resource would be used.

Pre-requisites

  • You have used the Azure Portal before and are comfortable deploying virtual machines in Azure IaaS.
  • Have obtained a license or eval license of SIOS DataKeeper

Deploying a File Server Failover Cluster Instance using the Azure Portal

To build a 2-node File Server Failover Cluster Instance in Azure, we are going to assume you have a basic Virtual Network based on Azure Resource Manager and you have at least one virtual machine up and running and configured as a Domain Controller. Once you have a Virtual Network and a Domain configured, you are going to provision two new virtual machines which will act as the two nodes in our cluster.

Our environment will look like this:

DC1 – Our Domain Controller and File Share Witness
SQL1 and SQL2 – The two nodes of our File Server Cluster

Provisioning the two cluster nodes (SQL1 and SQL2)

Using the Azure Portal, we will provision both SQL1 and SQL2 exactly the same way. There are numerous options to choose from including instance size, storage options, etc. This guide is not meant to be an exhaustive guide to deploying Servers in Azure as there are some really good resources out there and more published every day. However, there are a few key things to keep in mind when creating your instances, especially in a clustered environment.

Availability Set – It is important that both SQL1, SQL2 AND DC1 reside in the same availability set. By putting them in the same Availability Set we are ensuring that each cluster node and the file share witness reside in a different Fault Domain and Update Domain. This helps guarantee that during both planned maintenance and unplanned maintenance the cluster will continue to be able to maintain quorum and avoid downtime.

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Figure 3 – Be sure to add both cluster nodes and the file share witness to the same Availability Set

Static IP Address

Once each VM is provisioned, you will want to go into the setting and change the settings so that the IP address is Static. We do not want the IP address of our cluster nodes to change.

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Figure 4 – Make sure each cluster node uses a static IP

Storage

As far as Storage is concerned, you will want to consult Performance best practices for SQL Server in Azure Virtual Machines. In any case, you will minimally need to add at least one additional disk to each of your cluster nodes. DataKeeper can use Basic Disk, Premium Storage or even Storage Pools consisting of multiple disks in a storage pool. Just be sure to add the same amount of storage to each cluster node and configure it identically. Also, be sure to use a different storage account for each virtual machine to ensure that a problem with one Storage Account does not impact both virtual machines at the same time.

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Figure 5 – make sure to add additional storage to each cluster node

Create the Cluster

Assuming both cluster nodes (SQL1 and SQL2) have been provisioned as described above and added to your existing domain, we are ready to create the cluster. Before we create the cluster, there are a few Features that need to be enabled. These features are .Net Framework 3.5 and Failover Clustering. These features need to be enabled on both cluster nodes. You will also need to enable the FIle Server Role.

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Figure 6 – enable both .Net Framework 3.5 and Failover Clustering features and the File Server on both cluster nodes

Once that role and those features have been enabled, you are ready to build your cluster. Most of the steps I’m about to show you can be performed both via PowerShell and the GUI. However, I’m going to recommend that for this very first step you use PowerShell to create your cluster. If you choose to use the Failover Cluster Manager GUI to create the cluster you will find that you wind up with the cluster being issues a duplicate IP address.

Without going into great detail, what you will find is that Azure VMs have to use DHCP. By specifying a “Static IP” when we create the VM in the Azure portal all we did was create sort of a DHCP reservation. It is not exactly a DHCP reservation because a true DHCP reservation would remove that IP address from the DHCP pool. Instead, this specifying a Static IP in the Azure portal simply means that if that IP address is still available when the VM requests it, Azure will issue that IP to it. However, if your VM is offline and another host comes online in that same subnet it very well could be issued that same IP address.

There is another strange side effect to the way Azure has implemented DHCP. When creating a cluster with the Windows Server Failover Cluster GUI when hosts use DHCP (which they have to), there is not option to specify a cluster IP address. Instead it relies on DHCP to obtain an address. The strange thing is, DHCP will issue a duplicate IP address, usually the same IP address as the host requesting a new IP address. The cluster will usually complete, but you may have some strange errors and you may need to run the Windows Server Failover Cluster GUI from a different node in order to get it to run. Once you get it to run you will want to change the cluster IP address to an address that is not currently in use on the network.

You can avoid that whole mess by simply creating the cluster via Powershell and specifying the cluster IP address as part of the PowerShell command to create the cluster.

You can create the cluster using the New-Cluster command as follows:

New-Cluster -Name cluster1 -Node sql1,sql2 -StaticAddress 10.0.0.101 -NoStorage

After the cluster creation completes, you will also want to run the cluster validation by running the following command:

Test-Cluster

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Figure 7 – The output of the cluster creation and the cluster validation commands

Create File Share Witness

Because there is no shared storage, you will need to create a file share witness on another server in the same Availability Set as the two cluster nodes. By putting it in the same availability set you can be sure that you only lose one vote from your quorum at any given time. If you are unsure how to create a File Share Witness you can review this article http://www.howtonetworking.com/server/cluster12.htm. In my demo I put the file share witness on domain controller. I have published an exhaustive explanation of cluster quorums at https://blogs.msdn.microsoft.com/microsoft_press/2014/04/28/from-the-mvps-understanding-the-windows-server-failover-cluster-quorum-in-windows-server-2012-r2/

Install DataKeeper

After the cluster is created it is time to install DataKeeper. It is important to install DataKeeper after the initial cluster is created so the custom cluster resource type can be registered with the cluster. If you installed DataKeeper before the cluster is created you will simply need to run the install again and do a repair installation.

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Figure 8 – Install DataKeeper after the cluster is created

During the installation you can take all of the default options.  The service account you use must be a domain account and be in the local administrators group on each node in the cluster.

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Figure 9 – the service account must be a domain account that is in the Local Admins group on each node

Once DataKeeper is installed and licensed on each node you will need to reboot the servers.

Create the DataKeeper Volume Resource

To create the DataKeeper Volume Resource you will need to start the DataKeeper UI and connect to both of the servers.
10Connect to SQL1
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Connect to SQL2
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Once you are connected to each server, you are ready to create your DataKeeper Volume. Right click on Jobs and choose “Create Job”
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Give the Job a name and description.
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Choose your source server, IP and volume. The IP address is whether the replication traffic will travel.
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Choose your target server.
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Choose your options. For our purposes where the two VMs are in the same geographic region we will choose synchronous replication. For longer distance replication you will want to use asynchronous and enable some compression.
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By clicking yes at the last pop-up you will register a new DataKeeper Volume Resource in Available Storage in Failover Clustering.
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You will see the new DataKeeper Volume Resource in Available Storage.
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Create the File Server Cluster Resource

To create the File Server Cluster Resource we will use Powershell once again rather than the Failover Cluster interface. The reason being is that once again because the virtual machines are configured to use DHCP, the GUI based wizard will not prompt us to enter a cluster IP address and instead will issue a duplicate IP address. To avoid this we will use a simple powershell command to create the FIle Server Cluster Resource and specify the IP Address

Add-ClusterFileServerRole -Storage "DataKeeper Volume E" -Name FS2 -StaticAddress 10.0.0.201

Make note of the IP address you specify here. It must be a unique IP address on your network. We will use this same IP address later when we create our Internal Load Balancer.

Create the Internal Load Balancer

Here is where failover clustering in Azure is different than traditional infrastructures. The Azure network stack does not support gratuitous ARPS, so clients cannot connect directly to the cluster IP address. Instead, clients connect to an internal load balancer and are redirected to the active cluster node. What we need to do is create an internal load balancer. This can all be done through the Azure Portal as shown below.

First, create a new Load Balancer
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You can use an Public Load Balancer if your client connects over the public internet, but assuming your clients reside in the same vNet, we will create an Internal Load Balancer. The important thing to take note of here is that the Virtual Network is the same as the network where your cluster nodes reside. Also, the Private IP address that you specify will be EXACTLY the same as the address you used to create the SQL Cluster Resource.
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After the Internal Load Balancer (ILB) is created, you will need to edit it. The first thing we will do is to add a backend pool. Through this process you will choose the Availability Set where your SQL Cluster VMs reside. However, when you choose the actual VMs to add to the Backend Pool, be sure you do not choose your file share witness. We do not want to redirect SQL traffic to your file share witness.
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The next thing we will do is add a Probe. The probe we add will probe Port 59999. This probe determines which node is active in our cluster.
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And then finally, we need a load balancing rule to redirect the SMB traffic, TCP port 445 The important thing to notice in the screenshot below is the Direct Server Return is Enabled. Make sure you make that change.

445_ilb

Fix the File Server IP Resource

The final step in the configuration is to run the following PowerShell script on one of your cluster nodes. This will allow the Cluster IP Address to respond to the ILB probes and ensure that there is no IP address conflict between the Cluster IP Address and the ILB. Please take note; you will need to edit this script to fit your environment. The subnet mask is set to 255.255.255.255, this is not a mistake, leave it as is. This creates a host specific route to avoid IP address conflicts with the ILB.

# Define variables
$ClusterNetworkName = “” 
# the cluster network name (Use Get-ClusterNetwork on Windows Server 2012 of higher to find the name)
$IPResourceName = “” 
# the IP Address resource name 
$ILBIP = “” 
# the IP Address of the Internal Load Balancer (ILB)
Import-Module FailoverClusters
# If you are using Windows Server 2012 or higher:
Get-ClusterResource $IPResourceName | Set-ClusterParameter -Multiple @{Address=$ILBIP;ProbePort=59999;SubnetMask="255.255.255.255";Network=$ClusterNetworkName;EnableDhcp=0}
# If you are using Windows Server 2008 R2 use this: 
#cluster res $IPResourceName /priv enabledhcp=0 address=$ILBIP probeport=59999  subnetmask=255.255.255.255

Creating File Shares

You will find that using the File Share Wizard in Failover Cluster Manager does not work. Instead, you will simply create the file shares in Windows Explorer on the active node. Failover clustering automatically picks up those shares and puts them in the cluster.

Note that the”Continuous Availability” option of a file share is not supported in this configuration.

Conclusion

You should now have a functioning File Server Failover Cluster. If you have ANY problems, please reach out to me on Twitter @daveberm and I will be glad to assist. If you need a DataKeeper evaluation key fill out the form at http://us.sios.com/clustersyourway/cta/14-day-trial and SIOS will send an evaluation key sent out to you.

Deploying a Highly Available File Server in Azure IaaS (ARM) with SIOS DataKeeper

5 thoughts on “Deploying a Highly Available File Server in Azure IaaS (ARM) with SIOS DataKeeper

  1. Robert says:

    Is there MS documentation that mentions the reason for using subnetmask 255.255.255.255 for the ip resource (that has the same ip as the ILB)? I had built clustered sap systems on azure following MS docs and they definitely leave the subnetmask at default settings, which may end up as “255.255.255.0”. Would you say this setting is applicable to both Classic and ARM azure? One of my classic nodes lost network connectivity and the other node, while trying to make itself the owner of the role, complained that there is an ip conflict with the ILB ip. Weird that I haven’t see this error in similar scenarios before. I’m wondering if the 255.255.255.255 setting would have helped.

    1. daveberm says:

      I would say that is precisely the reason to use the /24 subnet mask. 255.255.255.255 is a host specific route, so there should never be an IP address conflict if you use it. It certainly was in the documentation when I originally wrote this article. Is the guidance different now?

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