Storage Spaces Direct (S2D) is the Microsoft implementation of software defined storage (SDS). This article briefly explains about the different types of volumes that can be created on a S2D cluster. Once you enable S2D using Enable-ClusterS2D cmdlet, it will automatically claim all physical disks in the cluster and forms a storage pool. On top of this pool you can create multiple volumes which is explained below.
Mirror
- Recommended for workloads that have strict latency requirements or that need lots of mixed random IOPS
- Eg: SQL Server databases or performance-sensitive Hyper-V VMs
- If you have a 2 node cluster: Storage Spaces Direct will automatically use two-way mirroring for resiliency
- If your cluster has 3 nodes: it will automatically use three-way mirroring
- Three-way mirror can sustain two fault domain failures at same time
- You can create two-way mirror by mentioning "PhysicalDiskRedundancy 1"
Parity
- Recommended for workloads that write less frequently, such as data warehouses or "cold" storage, traditional file servers, VDI etc.
- For creating dual parity volumes min 4 nodes are required and can sustain two fault domain failures at same time
new-volume -friendlyname "Volume B" -filesystem CSVFS_ReFS -storagepoolfriendlyname S* -size 1TB -resiliencysettingname Parity
- You can create single parity volumes using the below
Mixed/ Tiered / Multi-Resilient (MRV)
- In Windows Server 2012 R2 Storage Spaces, when you create storage tiers you dedicated physical media devices. That means SSD for performance tier and HDD for capacity tier
- But in Windows Server 2016, tiers are differentiated not only by media types; it can include resiliency types too
- MRV = Three-way mirror + dual-parity
- In a MRV, three-way mirror portion is considered as performance tier and dual parity portion as capacity tier
- Recommended for workloads that write in large, sequential, such as archival or backup targets
- Writes land to mirror section of the volume and then it is gradually moved/ rotated in to parity portion later
- Each MRV by default will have 32 MB Write-back cache
- ReFS starts rotating data into the parity portion at 60% utilization of the mirror portion and gradually as utilization increases the speed of data movement to parity portion also increases
- You should have min 4 nodes to create a MRV
new-volume -friendlyname "Volume C" -filesystem CSVFS_ReFS -storagepoolfriendlyname S* -storagetierfriendlynames Performance, Capacity -storagetiersizes 1TB, 9TB
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