RAID 6 is designed to be fault-tolerant — able to survive two drive failures. But when things go wrong, it’s usually not because the system failed… it’s because the rebuild did.

Silent sector errors, out-of-sync parity, or mistaken drive swaps can all cause RAID 6 arrays to fail in ways that look recoverable — until they’re not.

This page is your safe starting point.

We’ll walk you through what symptoms mean, what not to try on your own, and when to let ADR step in.


We’ll walk you through what symptoms mean, what not to try on your own, and when to let ADR step in.


Title: RAID 6 Dual-Failure, Rebuild Stalls, and Metadata Desynchronization

This in-depth note explains what happens inside the controller when parity math fails — from latent sector errors to NVRAM epoch drift. It’s the internal reference behind every RAID-6 page in this series.

Read the Full Technical Note TN-R6-001 →