Get better performance and efficiency with storage spaces direct

Do you want to build a highly available storage system using your local storage? Need software-defined storage that is quick to deploy and easy to maintain? Well, storage spaces direct, or S2D for short, might be your solution.

What is storage spaces direct?

Let’s start by understanding what storage spaces direct really is.

S2D takes internal storage from servers within a cluster and pools them together to give a highly resilient and scalable software-defined storage. In other words, S2D is a way of pooling disk storage to get better performance and efficiency.

Microsoft introduced this feature in Windows Server 2016 to simplify the deployment and management of software-defined storage, and also to expand the use of devices such as SATA. In addition, its hyper-converged architecture includes many features such as caching, RDMA networking, storage tiers, and more, so you can get one of the best efficiency and performance possible among this type of storage.

S2D features


S2D is an advanced version of storage spaces that was first introduced in Windows server 2012. Though it continues to have many features of storage spaces, still there are a few features that enhance its usability, and they are:

  • Nodes – S2D needs a minimum of two servers and can support a maximum of 16.
  • Uses SMB3 to communicate between servers.
  • Uses mirroring and erasure coding techniques to provide fault tolerance to virtual disks.
  • Stores three copies of data on different drives and cluster nodes, so it can support two simultaneous drive or server failures.
  • Supports ReFS file system, which is much better than NTFS, especially when it comes to handling metadata.
  • Automatically adds available drives to the storage pool.

Advantages and disadvantages of storage spaces direct

As with every product, storage space direct also comes with its own set of pros and cons.


The advantages of using storage space direct are:

  • Highly resilient, even against bit-rot and corruption.
  • The automatic configuration option simplifies setup. This configuration assigns disks just as the way the system sees them.
  • Excellent performance.
  • Works well with Windows Server failover clustering.
  • Highly flexible, especially when compared to the rigidity of RAID arrays.
  • Simple networking.


Though the disadvantages are far less than the benefits, it’s still important to know them.

  • Knowledge of PowerShell is helpful as the setup and management will be easier.
  • Slightly expensive, though it brings down the overall storage cost.
  • Needs a minimum of four nodes for optimal performance. Though it can support a scaled down infrastructure with just two nodes, it requires an additional tie-breaker mechanism in such a case.

Why use storage spaces direct?

Now that we’ve seen the basics, advantages, and disadvantages, you’re sure to be wondering about storage spaces direct and its application within your organization.

So, let’s see some reasons to use it and some situations where it will be most useful.

Easy to switch

One of the biggest selling points of S2D is its easy setup. You can switch from an industry-standard server to an S2D cluster in less than 15 minutes! Yes, you heard that right. That’s all it takes to make the switch. This means, your new S2D cluster will be up and running even before your customers have any idea about it.

Excellent performance

If you’re struggling with storage performance issues, S2D might be your solution. According to Microsoft’s blog, storage spaces direct can easily exceed 150,000 mixed 4k random IOPS per server. It also comes with a consistent low latency that speeds up the process of getting data. To top it, the very architecture of S2D as well as its built-in read/write cache greatly improves the performance of your storage cluster.

Highly resilient

Storage spaces direct is a highly resilient software-defined storage system. Its built-in resiliency features ensure the continuous availability of your storage. In most organizations, glitches happen when the hardware fails. But in an S2D setup, you have the option to simply replace the faulty hardware without having to make any major changes to the software side. And the best part – your customer won’t even know there was a problem with your storage system!


S2D is highly efficient when it comes to storage. According to Microsoft, storage spaces direct can deliver up to 2.4x more efficient storage with ReFS real-time tiers, and local reconstruction codes that minimize CPU consumption.


Storage spaces direct offers a ton of flexibility to your organization. S2D can be deployed in two ways, based on your existing system setup. It works when storage and compute functions are in separate clusters as well as when they are in a hyperconverged infrastructure. This flexibility makes it convenient to deploy S2D in both the setups to gain the maximum advantage. In fact, this flexibility of deploying it in a hyperconverged infrastructure is often seen as a cost-saving option for small organizations or those with many branches spread across a wide geographic area.

Detects latency and mirroring

S2D automatically detects drives within a pool based on their performance. For example, if a drive within a pool is exhibiting any kind of unusual performance, S2D identifies it right away, so the chance for latency issues is greatly reduced.


It can scale up to 16 servers and 400 drives and up to one petabyte of storage per cluster. To increase storage space, simply add more clusters or drives, and S2D automatically onboards them.



Storage spaces direct can be deployed in two ways.


In this option, storage and compute are in different clusters. A scale-out file server (SoFS) sits on top of S2D to give network-attached storage for all SMB3 file shares. So, you can scale the workload independently to meet your needs. This deployment is most ideal in large organizations that tend to use Hyper-V IaaS.


In this option, both compute and storage are present in the same cluster, so there is no need for any additional devices or software. This deployment is most ideal for small and medium businesses, and for those that have branches across different geographic regions.


Future of S2D

Windows Server 2019 is expected to have a more advanced version of S2D that will provide better efficiency and performance. An article by Kurt Mackie shows that Windows server 2019 will have the following upgrades or increases.

  • Raw capacity per cluster: 4 petabytes, up from the present 1 petabyte.
  • Raw capacity per server: 400TB, up from the current 100TB.
  • Number of volumes: 64, double of the current 32.
  • Maximum size per volume: 64TB, which is again double of the 32TB we have now.

These changes are expected to widen the reach and use of S2D.

S2D is a big step forward in the world of device storage and hopefully, Windows Server 2019 will make it even more efficient and high-performing.

Have you used storage spaces direct? Please share your opinion and thoughts with us in the comments section.

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