Default behavior of Storage Spaces Direct results in what capacity?

by Curious Blueprints   Last Updated September 14, 2018 16:00 PM

I have read the Drive Symmetry Considerations and the Deploy Storage Spaces Direct articles and I'm lookup to understand the default behavior of the Enable-ClusterStorageSpacesDirect command as it relates to capacity. According to the articles, the slower drives are configured to enable the largest amount of storage while still maintaining resiliency.

I'm looking at setting up a very small environment to experiment with this, and was wondering how much storage I will end up with? I have 2 servers and plan on configuring a witness. The two servers are identical. Each has 2 500GB SSDs and 3 HDDs: a 1TB, a 2TB, and a 3TB.

Based on what I have read, I understand that the pair of 500GB SSDs will be configured for cache. Where I get lost is what will happen to the HDD capacity. According to the above articles, different drive sizes across servers is supported, but may result in lost capacity, and different drive sizes within a server is supported. However, it makes no mention of stranded capacity.

Assuming I perform no extra configuration, would this setup result in 6TB of usable storage, 3TB (1TB for each drive), or something else entirely?

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