RAID 5 is popular because it allows for the loss of one drive without losing data. But what happens when a second drive fails during reconstruction (rebuild)?
The danger of URE (Unrecoverable Read Error)
During reconstruction, the RAID controller must read every sector of the remaining drives. If it encounters a single bad sector on another drive, the process fails and the array collapses.
Critical steps:
- Do not force the RAID to mount.
- Do not change the order of the drives.
- Clone all drives individually before attempting any logical reconstruction.
Professional recovery in these cases involves virtually reconstructing the RAID with parity parameters (rotation, stripe size) using drive images, bypassing damaged sectors.
