How to Expand Microsoft Storage Spaces Direct Volumes

As is the case with any other type of storage volume, the size of Microsoft Storage Spaces Direct volumes will inevitably need to be increased over time as data begins to accumulate. Fortunately, Microsoft has made it really easy to expand Storage Spaces Direct volumes on an as-needed basis.

Before I show you how to actually perform a volume expansion, I need to take a moment and talk about the volume footprint. The very nature of Microsoft Storage Spaces Direct means that volumes consume space on multiple servers. This is an extremely important consideration because it means that when you increase the volume size, you are actually going to be consuming significantly more storage space than you are allocating to the volume. The amount of overhead that will be required when expanding a Storage Spaces Direct volume varies depending on the volume architecture.

To give you a more concrete example, imagine that you have a 1 TB Storage Spaces Direct volume and that the volume’s resiliency is based on a three-way mirror. This would mean that there are three copies of the volume, and that the 1 TB volume is actually consuming 3 TB of physical disk space. Therefore, if you were to expand this volume from 1 TB to 2 TB, the expansion would require an additional 3 TB of disk space, bringing the volume’s total footprint to 6 TB.

So, with that said, let’s take a look at how you would go about increasing the size of a Microsoft Storage Spaces Direct volume.

Begin the process by opening the Storage Spaces Direct cluster in the Windows Admin Center.

The first thing that you need to know about the process is that as long as you have physical disk space available, you can increase a Microsoft Storage Spaces Direct volume for any reason. However, the Windows Admin Center will generate an alert if a volume is running low on disk space, and will actively encourage you to increase the volume’s capacity. You can view volume capacity related alerts by selecting the Volumes tab within the Windows Admin Center, and then looking at the Alert section. In Figure 1, the volumes are healthy and there are no alerts, but you can at least get a sense of what the interface looks like.

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Figure 1

If any capacity related alerts have been generated, they will show up here.

Regardless of whether you are increasing the size of a volume in response to a capacity alert or you need to add capacity to accommodate anticipated data growth, the process for increasing the volume size is the same. From within the Windows Admin Center, click on Volumes and then select the Inventory tab. The Inventory tab will show you all of the existing Storage Spaces Direct volumes. You can see what this looks like in Figure 2.

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Figure 2

The Inventory tab lists your Storage Spaces Direct volumes.

Click on the volume that you want to expand. This will cause the Windows Admin Center to display the volumes details. To expand the volume, click on the Resize icon, which you can see in Figure 3.

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Figure 3

Click on the Resize icon to resize the volume.

At this point, the Windows Admin Center will display a dialog box that gives you the option to resize the volume. As you can see in Figure 4, this dialog box tells you the current volume size and gives you the option of specifying a new size for the volume. The important thing to pay attention to is that this dialog box shows you not only the volume size, but also the volume footprint. It also shows you what the footprint will be after your intended expansion. In this case, for example, I am increasing the volume size from 20.9 GB to 30 GB. If you look at the Resiliency option (on the main part of the screen), you can see that this volume is three-way mirrored. As such, the extra 9.1 GB of volume space will require 27.3 GB of physical disk space, as expressed within the figure.

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Figure 4

This is the interface used to expand a Storage Spaces Direct volume.

One thing that you might have noticed in the figure above is that there is no OK button. When you press Enter, the volume expansion will begin. Be careful not to press Enter before you are actually ready to commit to the changes you have entered on the screen.

When you expand the Microsoft Storage Spaces Direct volume, it may take a few minutes for the Windows Admin Center to reflect the change. Eventually, though, the new capacity should be reflected in the volume details. If a low-capacity alert had previously been generated, that alert will also eventually go away on its own.