Windows Storage Spaces Direct

  • Microsoft is bringing out a new storage feature called Windows Storage Spaces Direct.

    Windows Server Technical Preview introduces Storage Spaces Direct, which enables building highly available (HA) storage systems with local storage. This is a significant step forward in Microsoft Windows Server software-defined storage (SDS) as it simplifies the deployment and management of SDS systems and also unlocks use of new classes of disk devices, such as SATA and NVMe disk devices, that were previously not possible with clustered Storage Spaces with shared disks.

    To help understand Storage Spaces Direct, let’s examine Storage Spaces in Windows Server 2012 R2 HA storage systems. In Windows Server 2012 R2, an HA system using Storage Spaces requires disks to be physically connected to all storage nodes. To allow for the disks to be physically connected to all storage nodes, they need to reside in an external JBOD chassis with each storage node having physical connectivity to the external JBOD. Also, only SAS disk devices are supported because, unlike SATA, SAS supports multi-initiator. Because of these requirements, we have nicknamed this deployment “Storage Spaces with Shared JBOD” in contrast with Storage Spaces Direct. Figure 1 illustrates a “Storage Spaces with Shared JBOD” deployment.

    storage spaces direct

    This could be a very interesting, competitive feature coming from Microsoft. Anyone playing with it yet?

  • “Storage Spaces with Shared JBOD” provides many benefits compared to past HA storage systems. However, requiring that disk devices are physically connected to every single node limits the type of disk devices that can be used and can lead to complex SAS fabric configurations, especially as these deployments scale out. With Windows Server Technical Preview Storage Spaces Direct, you can now build HA Storage Systems using storage nodes with only local storage, which is either disk devices that are internal to each storage node (Figure 2), or disk devices in JBODs where each JBOD is only connected to a single storage node (Figure 3). This completely eliminates the need for a shared SAS fabric and its complexities, but also enables using devices such as SATA disks, which can help further reduce cost or improve performance. The diagram below illustrates a “Storage Spaces Direct” deployment.

    storage spaces direct

  • Overview

    Storage Spaces Direct seamlessly integrates with the features you know today that make up the Windows Server software defined storage stack, including Scale-Out File Server, Clustered Shared Volume File System (CSVFS), Storage Spaces and Failover Clustering. Figure 4 below illustrates the “Storage Spaces Direct” stack:

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