Layer 2

Why 2 bays or 4

Bay count is not a brand preference. It follows the planning target and the media label, using mutually exclusive rules.

Typical 2-bay

Synology DS224+

A 2-bay that will serve a mostly Direct Play library. Still a mirror.

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• Mirror — two NAS-rated drives, usable ≈ one
• Plus-class 2-bay versus the value model
• Direct Play library, not a transcode lab pick

Not for: Households that may need hardware transcoding, or a target at 8 TB and above.

Typical 4-bay

Synology DS425+

A household that crossed the 8 TB line and wants a current compact 4-bay.

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• Single-parity class — four drives, usable ≈ three
• UK public page lists 4 bays and 2.5GbE
• No hardware-transcode claim copied from that page

Not for: A verified hardware-transcode enclosure. The public UK page does not claim that.

The actual thresholds

Transcode-class is editorial, not a lab result. Our current set has no enclosure classified as verified hardware-transcode capable, so that label returns no enclosure to buy.

Half-open intervals

7.96 TB stays on the 2-bay rule; 8.00 TB crosses. Rounding is display-only and does not change the match. Rules must not overlap — if they did, the engine returns an error instead of picking a favourite.

Why not always four

A 4-bay is quieter to grow into and cheaper per usable terabyte once you need the space. It is also more to buy, more to power, and more to fill on day one. Below 8 TB of planning target, a 2-bay mirror is the honest household default.