13 Jun 2015

Getting Started with Storage Replica and Storage Spaces Direct in Server 2016 Technical Preview 2

With Windows Server 2016,  Microsoft is once again going to mix up the storage vendor market. Continuing the ASD (all Software defined) strategy, some new cool features arise with the new version. If you’re familiar with Storage Spaces / JBOD architectures already you might now, that there are some limitations today, which may prevent some customers adapting this technology. The current version does not allow:

  • Storage level replication
  • Distributing storage across hosts with non-shared storage
  • Hyper-converged setups (Hypervisor and Storage on same box with node based scaleout)

With Windows Server 2016, Microsoft delivers solutions for both requirements. In this article you will get an overview and how to configure the new stuff.

Disclaimer: The showed features and requirements are related to the public available “Technical Preview 2” Release and may change in future or RTM releases.

Storage Spaces Direct

By now, with Windows Storage Spaces, we where able to create virtual disks across physical disks sitting in different enclosures connected via SAS bus. Failover Clustering together with shared SAS was used to create Scale out File Servers, mainly to provide highly available and performant storage for virtual machine and SQL database workloads. Although this is very nice and powerful, customers missed some enterprise features. We where not able to spread storage pools across physical separated locations, meaning out of a single rack.

With the DAS model of Storage Spaces (Storage Spaces Direct) this is going to change dramatically. We can now create Spaces across physical-separated storage boxes. The storage nodes can have direct attached storage (inline) or local storage from any supported JBOD. The Storage Pool and the virtual disks (Spaces) can now contain local, non-shared physical disks from different hosts, connected via a reliable and fast ethernet connection. Microsoft uses a SW based storage bus bases on the proved SMB3 technology leveraging all well known features such as:

  • Transparent Failover
  • Multichanneling
  • SMB Direct (SMB over RDMA)


Model 1 (Compute and Storage are separated)

Image source: (c) Microsoft


Model 2 (Hyper-Converged, Compute and Storage on same node)


Image source: (c) Microsoft



  • min. 4 Local SAS / SATA / NVMe disks per node
  • Min. of 4 nodes
  • Min. 1 flash Disk per node
  • 10  / 40 Gbps RDMA NIC in each node
  • 64 GB RAM for each node
  • Internal disks to be connected via non-Raid controller or JBOD disks via non-RAID SAS HBA
  • Basic requirements for Failover Clustering apply, except the need for shared storage

How to test / validate Storage Spaces Direct

The following TechNet documentation can be used as a guide to configure S2D



Storage Replica

SR is a volume based synchronous or asynchrounous storage mirroring feature in Server 2016. The feature is totally HW agnostic, meaning the underlying volumes can be either SAS, FC / FCoE or iSCSI type. The replication works on block level. This said, it doesn’t matter of wich type the source and target volumes are beside these requirements. The feature is implemented using a filter driver sitting low in the storage / FS stack.


Types of Storage Replications

Image source: (c) Microsoft


  • Same volume size on source / destination
  • Log Disk (SSD / Flash) on both source and destination
  • Same underlying disk geometry
  • Same underlying format type  (GPT only)
  • Same underlying FS block size

Additionally the following requirements apply for synchronous replication scenarios

  • 8Gbps transfer troughput
  • Continous < 5ms round trip at 1472 non-fragmented bytes packet size

How to test / validate the scenario

The following TechNet documentation can be used as a guide to configure SR



I’ve stressed both of the technologies in my tests quite heavily with the current public version of TP2. From a functional perspective I can say that almost everything is working as expected, while on the performance side, there’s room for improvement, but this will evolve as new builds will come out. I can highly recommend you download the Windows Server Technical Preview and kick the tires, try this amazing stuff and be prepared 🙂