RAID Rebuild Time Estimator

Estimate how long an array runs degraded after a drive fails.

What you provide

A 7,200 rpm drive sustains roughly 1,200 Mbps sequentially. Controllers usually rebuild slower.

Result

CHECK

About 127.0 hours degraded on a RAID 5 rebuild

For 127 hours this array survives no further failures. Drives bought together tend to fail together, they are the same age and have done the same work, and a rebuild puts every one of them under sustained load. Two practical mitigations: lower the rebuild priority only if you can accept the longer window, and make sure a genuine backup exists, because a rebuild is a repair and not a copy.

Diagnostic telemetry
Array
RAID 5, 5 × 8 TB
Data read to rebuildParity reads every surviving member
32.0 TB
Idle array
88.9 h
Serving 30% load
127.0 h
Degraded window
high
Second failure toleratedAnother failure during rebuild loses the array
no

What this cannot tell you

  • An estimate from the figures you enter. It cannot see your array, your controller or your drives.
  • Real rebuild times vary enormously with controller behaviour, rebuild priority settings and how full the array is. Treat this as an order of magnitude, not a schedule.

Take this with you

RAID Rebuild Time Estimator on RunTheTests — free browser-based sysadmin tools, no sign-up.