You have a failover cluster named Cluster1 that contains four Windows Server nodes named Node1, Node2, Node3, and Node4. You need to deploy a Storage Spaces Direct virtual disk to Cluster1. You add th

This question tests understanding of Storage Spaces Direct (S2D) cache tier behavior with three media types and how to calculate usable pool capacity by excluding cache-only drives.

Implement and manage Windows Server high availability

Question

You have a failover cluster named Cluster1 that contains four Windows Server nodes named Node1, Node2, Node3, and Node4. You need to deploy a Storage Spaces Direct virtual disk to Cluster1. You add the following disks to each node:
Three 512-GB NVMe disks
Three 3-TB HDD disks
Three 1-TB SSD disks
On Cluster1, you enable Storage Spaces Direct and add the new disks.
What is the total amount of disk space available for the Storage Spaces Direct virtual disk, and which operations are cached in the SSD and HDD disks? To answer, select the appropriate options in the answer area.

Explanation

This question tests understanding of Storage Spaces Direct (S2D) cache tier behavior with three media types and how to calculate usable pool capacity by excluding cache-only drives.

Approach. In S2D with three media types (NVMe, SSD, HDD), NVMe drives become a write-only cache for the SSD tier, and SSD drives become a read/write cache for the HDD tier. NVMe drives are excluded from pool capacity because they serve exclusively as cache. The total raw pool capacity is therefore: (3 × 1 TB SSD × 4 nodes) + (3 × 3 TB HDD × 4 nodes) = 12 TB + 36 TB = 48 TB. Regarding cache operations: NVMe caches writes only to the SSD tier (because SSD reads are already fast enough to not need caching), while SSD caches both reads AND writes to the HDD tier (because HDD reads are slow and benefit from caching). This tiered cache behavior is automatic and is determined by drive media type - no manual configuration is required.

Concept tested. Storage Spaces Direct (S2D) three-tier cache hierarchy: how NVMe, SSD, and HDD roles are automatically assigned (cache vs. capacity), which drive types are excluded from pool capacity, and the difference in cache operation types - write-only cache for all-flash tiers (NVMe→SSD) vs. read+write cache for spinning disk tiers (SSD→HDD).

Reference. Microsoft Docs: Understanding the cache in Storage Spaces Direct - https://learn.microsoft.com/en-us/windows-server/storage/storage-spaces/understand-the-cache

Topics

#Storage Spaces Direct (S2D)#Failover Clustering#Storage Tiers#Caching

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