This article outlines the process of adding a disk to a SQL Server Failover Cluster Instance. The screenshots in this article are taken from a Windows 2012 R2 server, all steps are valid for newer versions but the validation test part. Please, check the “Tips and Warnings” section for Windows Server 2016 and 2019

• 1 Prerequisites
• 2 Process Steps
  • 2.1 Online and Initialize the disk for use in Windows.
  • 2.2 Format the disk
  • 2.3 Add disk to the Microsoft Failover Cluster Expand All
  • 2.4 Windows Failover Cluster Storage Validation  Expand All
  • 2.5 Add disk to the Failover Cluster Instance () Expand All
  • 2.6 Add the disk as a Dependency for the Failover Cluster Instance Expand All
• 3 Tips & Warnings
• 4 Closure code
• 5 Related Links
• 6 Summarized Bullet Points from Last Revision
• 7 Article History

Prerequisites

• Privileges to manage the Windows Failover Cluster hosting the SQL Server Instance (e.g. Domain Credentials within the local Administrators Group)
• Disk has already been presented to the cluster nodes hosting the SQL Server Failover Cluster Instance by SAN, Virt, MPC or whoever.

Process Steps

Online and Initialize the disk for use in Windows.

1. Open up diskmgmt.msc and find the unallocated disk.
2. Right-click in the left section (Disk #) and choose Online (this step must to be performed on all cluster nodes).
3. Right-click in the left section (Disk #) and choose Initialize.
   1. From the pop-up window, ensure only the disk you’re working on is selected, select the GPT radio button and click OK.

Format the disk

• This step assumes we’re adding a new disk/volume that does not contain customer data.
• When working with an existing disk/volume, coordinate with the customer before formatting in order to prevent data loss.

1. Right-click on the unallocated space and choose Create new Simple Volume.
2. Follow the wizard:
   1. Assign the drive letter specified by the customer
   2. Specify 64k block size.
   3. Define a friendly drive label. (In my examples in this article, I’ve used drive letter E: and label E_TEMP.)

Add disk to the Microsoft Failover Cluster 

1.  Open cluadmin.msc and expand the cluster. Expand,See (A).
2. 
3. Add Disk within cluadmin.msc
4. 
5. Select the disk that you want to add.
   1. Typically you will only see 1 disk available (as all other disks are either not suitable for clustering or have already been added). If more than 1 disk shows up, use the Disk # displayed under the “Disk Info” header to correlate it to the Disk # in diskmgmt.msc.
6. Check the box and click OK.
7. Rename the Cluster Disk. This will help avoid the confusion of the generic name “Cluster Disk #” vs “Disk #” in diskmgmt.
   1.  While on the Disks page, right-click the new Cluster Disk # (A) in the top-center pane and choose Properties (B).
   2.  Change Cluster Disk # to a more friendly name, then click Apply and OK. It’s usually a good idea to use the same friendly name you used to label the drive in diskmgmt. As such, I’m using E_TEMP in my example.

Windows Failover Cluster Storage Validation  

IMPORTANT

Cluster Validation tests ARE NOT disruptive when excluding the “Storage” option or only including disks that are “Assigned To” to the “Available Storage” cluster group.

Downtime WILL occur when performing a Cluster Validation test that includes the “Storage” option with disks that are in use by an online cluster group other than “Available Storage” (e.g. SQL Instances, File Services, etc).

Steps below are valid for clusters running on Windows Server 2012 R2. Please, check the section “Tips & Warnings” for clusters running on Windows Server 2016 or 2019.

1.   In Cluster Administrator, select Disks in the navigation pane and verify the newly added Disk is in Available Storage.  
2. Start the Validate a Cluster option in the main Cluster Administrator window
   1.  In the Validate a Configuration Wizard choose Run Only The Tests I Select     
3.  Deselect all but the Storage option
4.  Select the disk in Available Storage
5.  Allow the Wizard to take the disk offline and run the tests.
6.  View the report and verify the tests completed
7. Click on “View Report…” to verify the disk is suitable for use in a Microsoft Failover Cluster.

Add disk to the Failover Cluster Instance

1. Now that the drive has been added to the cluster as available storage and given a friendly name, we can add it to our SQL Server instance.
   1. Windows Server 2012 and newer, select Roles (A), right-click the appropriate SQL Server (B) instance in the top-center pane and choose Add storage (C).
   2. Windows Server 2008 and R2, expand Services and Applications in the left pane, right-click on the appropriate SQL Server instance and choose Add storage.
2. Select the disk or disks you want to add
   1. You should see the disk listed by the friendly name you gave it earlier, but if you’re unsure, you can expand to see drive letter. Check the box (A) and click OK.

Add the disk as a Dependency for the Failover Cluster Instance 

A clustered SQL Server Instance will not be able to utilize a disk until it has been configured as a dependency of the SQL Server Cluster Group.

1. Open the “Properties” of the SQL Server Failover Instance
2. 
3. Add the disk to the list of Dependencies
   
   
   1. Change to the Dependencies (FIG. 1-A) tab
   2. Click on Click here to add a dependency (FIG. 1-B)
   3. Ensure AND is selected, then click the down-arrow (FIG. 2-A) and choose the new Cluster Disk (FIG. 2-B)
   4. Click Apply and OK. Now you’re done!

Tips & Warnings

• A clustered SQL Server instance will not be able to utilize a disk until it has been configured as a dependency of the SQL Server Cluster Group.
• In case a cx asks add a disk as a mount point, check the following MSFT article Adding mount points to a WSFC SQL Cluster ( FCI ) Instance.
• To add additional mount points to an existing clustered Mount Root, you must place the mount root into maintenance mode first. Otherwise, you will receive an error message stating “Parameter Incorrect”. To do this, follow these steps:
  1. Start Failover Cluster Manager
  2. Navigate to Storage
  3. Right-click on the disk you are going to work on
  4. Go to More Actions and select the desired option
  Please note that this process will result in downtime, so it’s important to inform your customers (CX) ahead of time.