Combines the internal drives of between two and 16 servers in a cluster into highly available, software-defined storage. It is part of Windows Server Datacenter.
Also called S2D.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains Storage Spaces Direct in context, with comparison tables and the common traps.
Terms in this definition
- Internal
The API Management VNet mode where the gateway can be reached solely through a private IP address.
- General-purpose v1
The older storage account kind (
Storage), which lacks access tiers, Archive and premium file shares and retires on 13 October 2026. Converting to ZRS requires first upgrading to GPv2, a one-way change. - Datacenter
A building packed with racked servers that has its own electricity supply, cooling and network links. Microsoft gathers these buildings into Azure regions, and as a customer you pick the region, never which building your resources land in.
Related terms
- Mirror-accelerated parity
A Storage Spaces Direct ReFS volume split between a mirrored portion and a parity portion. New data is written to the mirror first and later shifted to parity, which uses capacity more efficiently.
- Nested resiliency
Designed only for two-server Storage Spaces Direct clusters, either as nested two-way mirror or nested mirror-accelerated parity. Volumes stay available even when a drive and a server fail at the same moment.
- RAID
Grouping drives for speed or resilience, by mirroring (level 1) or parity (level 5), say. Software-defined versions come from Storage Spaces, and Storage Spaces Direct expects pass-through controllers.
- Storage bus layer cache
The Storage Spaces Direct cache that pairs each server's quickest drives with its slower ones, soaking up writes and data that is read often.