RAID 50 Failed and One Stripe Group Is Missing
RAID 50 stripes data across two or more RAID 5 groups. If one lower group disappears, the controller cannot present the complete virtual disk even when the other group remains available. Recovery begins by identifying and reconstructing the lower groups separately.
Do not recreate the missing group, force members online, or initialize a replacement virtual disk. Preserve every original and replacement member.
What this condition means
A missing group can result from a genuinely unreadable member, changed group membership, lost configuration, controller or enclosure trouble, an interrupted rebuild, or metadata the controller no longer accepts.
The group label describes what the controller can assemble now. It does not prove that every member in that group is physically failed or that the data has been erased.
What to record
- Server, controller, enclosure, firmware, and expected RAID 50 capacity
- Expected group count and members per RAID 5 group
- Bay, serial number, size, and displayed status of every drive
- Which group is missing and the last time the array mounted normally
- Every replacement, rebuild, import, force-online, recreation, or repair already attempted
What not to do
- Recreate the missing RAID 5 group
- Force reported members online
- Initialize or format a newly presented virtual disk
- Discard members labeled failed or foreign
- Run filesystem repair before both RAID layers are validated
How ADR evaluates it
ADR checks member identity, readability, metadata, and parity within each lower RAID 5 group.
After defensible lower groups are established, ADR tests the stripe joining them and validates the expected filesystem and priority data before recovery to separate storage.
What happens next
The original controller does not have to restore the missing group. ADR can evaluate the complete member set independently and determine whether the two RAID layers can be reconstructed.