RAID 1 dual failure
RAID 1 duplicates blocks across members, but degraded operation, bad sectors and interrupted rebuilds can leave two disks with different generations and different readable regions.
Understand the symptom
A healthy mirror maintains matching writes, but once one disk drops out the surviving member becomes newer. If that member then develops errors or a rebuild partially copies data to another disk, no single device may contain the best version of every block. Imaging each independently allows a controlled composite rather than choosing blindly.
What you may see
The only current member may be physically unstable or contain unreadable sectors.
The target may contain a mixture of copied and old or empty regions.
One member may be stale, misidentified or written outside normal mirror operation.
Boots or mounts may expose different data depending on which disk becomes active.
Protect the source
Selecting source and target incorrectly destroys an alternate generation.
Applications and filesystem journals can widen differences between members.
A failing source needs controlled imaging that prioritizes readable regions.
Do this now
Prevent automatic rebuild, resync, boot and application writes.
Record which disk failed first, which remained online and how far any rebuild progressed.
Keep original, removed, replacement and target disks without reusing them.
Timestamps and serials help establish the data generation on each member.
NEPFOSYS process
NEPFOSYS evaluates member timestamps, metadata, readability and failure sequence.
Each mirror member is acquired separately with errors and unreadable ranges documented.
The most coherent current filesystem is assembled from the strongest available member data.
A clear next step
Start a case with the exact symptoms, incident timeline, prior attempts, encryption details, and the files that matter most. NEPFOSYS will route the case to the appropriate DFW intake or nationwide mail-in path.
Start with a case reviewQuestions, answered
Only while both receive every write. Degraded use, stale members and partial rebuilds can create different generations.
No. That destroys the alternate copy. Image both to separate destinations before choosing or combining data.
Potentially. Different members may read different weak regions, but generation consistency must be preserved.
DFW local · Nationwide mail-in