RAID 6 Data Recovery
RAID 6 uses two independent parity blocks so it can survive two drive failures. It is the standard choice for large NAS units and storage servers with high-capacity drives, including Synology and QNAP systems with eight or more bays.
Even so, RAID 6 arrays fail – usually when a third drive drops out during a long rebuild, or when the controller or metadata fails. Recovery requires calculating both parity schemes, which varies between vendors.
Common RAID 6 Failures
- Three or more drives failed or dropped out
- Rebuild failure on 16TB, 20TB or larger drives
- Controller, backplane or expander failure
- Lost configuration after firmware update
- File system corruption (NTFS, ReFS, ext4, XFS, Btrfs, ZFS)
How We Recover a RAID 6 Array
RAID 6 stores two different parity blocks: simple XOR parity (P) and a Reed–Solomon style syndrome (Q). Controllers from Dell, HPE, Broadcom, Adaptec and NAS vendors lay these out differently, so we identify the exact scheme before rebuilding. This allows two missing members to be regenerated. For ZFS RAID-Z2 pools the stripe width varies per block, so we rebuild from ZFS’s own metadata rather than a fixed geometry.
Before You Do Anything
If your array has failed: do not force a rebuild, re-initialise the array, run CHKDSK/fsck, or swap drives between slots. Label every disk with its slot number, shut the system down cleanly if you can, and call us on 020 7064 4996. Most unrecoverable RAID cases we see were made worse by a rebuild attempted on the wrong disk.
See RAID & server data recovery for the servers, controllers and NAS systems we support.
Frequently asked questions
Is RAID-Z2 the same as RAID 6?
It is ZFS’s equivalent, using two parity blocks. We recover ZFS RAID-Z1, RAID-Z2 and RAID-Z3 pools from TrueNAS, QNAP QuTS hero and other ZFS-based systems.
Free assessment, no obligation. Call 020 7064 4996 or use the form on this page – an engineer will tell you what can be recovered and what it will cost. Book online · Pricing · Locations