Rebuild and resilver planning

Plan the degraded window before a drive fails.

Model the data scope and limiting transfer path, account for active workloads, and compare the resulting rebuild window with the time your storage and recovery plan can tolerate.

Degraded-state planner

Estimate a rebuild window from the path you can measure.

Turn the reconstruction scope and three throughput boundaries into a transfer floor and a load-adjusted planning window, then compare that window with the degraded-state limit you can accept.

View assumptions and sources →

The values below are editable planning baselines. Change the few inputs you know; open Advanced assumptions only when they change your decision.

Advanced assumptionsUse measured aggregate rates when available; the editable starting values create a planning envelope you can refine.
Raw transfer bottleneck——
Planning throughput——
Transfer floor—Data scope ÷ raw bottleneck, before foreground activity and planning efficiency.
Planning window——
Degraded-state target——
Protection during rebuild——

Transparent pressure ladder

See where the planning rate is reduced.

StageInput or limitRate after stageDecision meaning
Raw bottleneck——Slowest entered read, write, or controller path.
Foreground workload——Capacity left after reserving throughput for active services.
Planning efficiency——Scheduling, seeks, retries, and implementation pressure represented by one editable factor.
Next decision

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Rebuild brief

Keep the degraded window with the response checks.

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Next decision

Verify the replacement procedureReturn to RAID capacity

Plan tools

Keep this useful version close, shareable, and easy to revisit.

Reset inputs

Optional support

Keep practical planning tools available.

If this result made the next decision clearer, an optional contribution helps cover hosting, source reviews, and continued improvements.

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Editorial record

Maintained by Make Your Own Tools to turn “Store data safely” into a defined capacity, bays, redundancy, and recovery baseline. The references below provide the technical context for this planning path. Its calculation rules and planning assumptions are documented in the methodology, and affected calculations pass regression checks before the review date advances.

Last reviewed
Evidence set
2 primary references
Calculation coverage
1 affected rule checked
Read methodology →
Planning scope
Pre-incident rebuild, repair, or resilver window planning where the reconstruction scope and aggregate throughput boundaries can be entered or measured.
Next check
A guaranteed completion time, latent media errors, controller failure, thermal throttling, platform scheduling behavior, or simultaneous faults outside the selected layout boundary.
Synology storage pool repair guidanceOfficial degraded-pool repair workflow, supported protected layouts, replacement-drive requirements, and repair-mode behavior.Open source ↗TrueNAS disk replacement and resilver guidanceOfficial replacement workflow and resilver boundary for a degraded ZFS pool.Open source ↗