Expansion

Plan drive replacement before buying larger disks

Before buying a single larger drive, model the target layout and verify the platform’s rules for when extra capacity becomes usable.

Decision 01

Model the end state

Write down every current drive size, the proposed replacements, the intended pool layout, and the free bays. Do not infer the result from one replacement alone.

Decision 02

Verify platform rules

Synology, ZFS-based systems, and Unraid have different expansion behavior. Follow the official documentation for the exact release and platform.

Decision 03

Protect before migration

Confirm independent recovery copies and drive health before a replacement sequence. Expansion is a change operation, not just a shopping task.

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Related decisions

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Sources and scope

Last reviewed 2026-07-13. This page separates the decision it supports from the facts that still require a platform or model-specific check.