Sometimes, a faulty RAID controller writes corrupted data to both mirror disks simultaneously. Recovery involves treating and analyzing each disk independently to search for previous versions in metadata or healthy file fragments that the RAID's automatic replication has not yet overwritten. [Image illustrating RAID 1 data mirroring between two disks]
RAID 1 should protect against failures, but a failing hardware controller or a firmware issue can corrupt both disks at the same time. In these cases, connecting a single disk is useless: both reflect the corruption. Specialists disconnect the disks and treat them individually as independent units, scanning previous versions of metadata (snapshots), file system journals, or sectors not overwritten by the faulty synchronization. With forensic tools, minimal differences between disks are compared to reconstruct the most coherent version. This approach saves data that seemed irrecoverably lost due to the mirror's own redundancy.
