Hardware and RAID configuration:
There were 3x2TB hard drives from a RAID-Z.
A customer had a RAID-Z consisting of three 2TB drives. One of the drives went bad and the RAID-Z was forced to operate in degraded mode.
A technician tried to replace the bad drive but swapped out a good drive by mistake. The rebuild failed and the RAID-Z went down.
The customer tried unsuccessfully to import and scrub the zpool.
We ran an analysis and found that this was a RAID-Z with single parity (equivalent to RAID 5). One drive was stale. There were some corruptions but the ZFS metadata was mostly intact.
We determined the correct RAID-Z settings and used them in File Scavenger® to reconstruct the original ZFS volume and recover the original data.
File Scavenger® supports ZFS and single and double parity RAID-Z.
We were able to recover the files and directory tree in the ZFS pool (1.8 million files totaling 660 GB) using the configuration below:
- RAID: RAID-Z single parity.
- Number of drives: 3.
Drive 1: missing
Drive 2: PhysicalDrive1
Drive 3: PhysicalDrive3
Looks great. It looks like it is retaining the mod dates as well. That is really good work. Thank you!
Read the in-depth technical paper ZFS and RAID-Z recoverability and performance.