Plymouth Data Recovery — No.1 RAID 1 (Mirror) Recovery Specialists (25+ years)

From home users to multinationals and public-sector teams, Plymouth Data Recovery has decades of hands-on experience recovering RAID 1 mirror sets across software & hardware RAID, NAS, large NAS and rack servers. We work forensically: stabilise each member → acquire read-only clones → reconstruct the mirror virtually → repair filesystems on the clone only. Free diagnostics with clear options before any paid work begins.

Platforms & vendors we support

RAID / controllers: Dell PERC, HPE Smart Array, LSI/Avago/Broadcom MegaRAID, Adaptec/Microchip, Areca, Intel RST/e, HighPoint, Promise, mdadm/LVM (Linux), Windows Dynamic Disks / Storage Spaces, Apple/macOS RAID Assistant, ZFS/Btrfs mirrors.

Filesystems & LUNs: NTFS, ReFS, exFAT, FAT32, APFS, HFS+, ext2/3/4, XFS, Btrfs, ZFS, VMFS (VMware), iSCSI/NFS-backed LUNs.

Media: 3.5″/2.5″ HDD (SATA/SAS), SATA SSD, NVMe (M.2/U.2/U.3/AIC), 512e/4Kn.

NAS / external RAID brands in the UK & popular models (15)

(Representative brands & high-volume models we commonly recover; if yours isn’t listed, we still support it.)
Synology (DS923+, DS1522+, DS224+, RS1221+); QNAP (TS-464/TS-453D, TVS-h674, TS-873A); Netgear ReadyNAS (RN424/RN524X); Western Digital (WD) (My Cloud EX2 Ultra, PR4100); Buffalo (TeraStation TS3410/5410, LinkStation LS220D); Asustor (AS6704T, AS5304T); TerraMaster (F4-423, F5-422, T9-423); LaCie (Seagate) (2big/6big/12big); TrueNAS / iXsystems (Mini X/X+, R-Series); Drobo* (5N/5N2); Lenovo/Iomega* (PX4-300D/PX6-300D); Zyxel (NAS326/NAS542); Promise (Pegasus R-series, VTrak); Seagate (Business Storage/BlackArmor*); OWC (ThunderBay 4/8).
*legacy but still widely encountered.

RAID rack-server platforms & common models (15)

Dell EMC PowerEdge (R650/R750/R760, R740xd), HPE ProLiant (DL360/DL380 Gen10/Gen11), Lenovo ThinkSystem (SR630/SR650), Supermicro (1029/2029/6049; SuperStorage 6029/6049), Cisco UCS (C220/C240 M5/M6), Fujitsu PRIMERGY (RX2530/RX2540), QCT (D52B/D52BQ), Inspur (NF5280 M6/M7), Huawei (FusionServer Pro 2288/5288), ASUS Server (RS520/RS700), Gigabyte Server (R272-Z/R282-Z), Tyan (Thunder/Transport), Areca (ARC-1883/1886 builds), Adaptec by Microchip (SmartRAID 31xx/32xx), iXsystems/TrueNAS R-Series (R10/R20 JBOD/HBA).

Our RAID 1 recovery workflow (what we actually do)

1. Stabilise & image each member with hardware imagers (HDD: per-head zoning/timeout-ECC control; SSD/NVMe: read-retry/voltage stepping/thermal control). No writes to originals.

2. Member health/epoch analysis — S.M.A.R.T., error heatmaps, write-order evidence, controller metadata; choose an authoritative mirror or compose a best-of-both image per LBA.

3. Virtual mirror assembly — Build a logical RAID 1 from the best blocks; if divergence exists, block-level voting by checksums, timestamps, filesystem coherence.

4. Filesystem/LUN repair on the virtual set — NTFS/ReFS/APFS/HFS+/ext/XFS/Btrfs/ZFS/VMFS metadata repair; mount read-only and export.

5. Verification — Per-file MD5/SHA-256, sample open, and a recovery report.

Note: RAID 1 has redundancy, but long-ignored mirror divergence, failed rebuilds or subsequent user “repairs” can reduce recoverability. We always prefer the earliest, most-coherent epoch.

Top 100 RAID 1 errors we recover — with technical approach

Format: Issue → Diagnosis → Lab recovery (using cloned members & a virtual mirror model).

Member disk / media (HDD/SSD/NVMe) — 1–20

1. Single-disk mechanical failure → Head/SA tests → Donor HSA swap; per-head imaging; use healthy mirror as authority.

2. Both members failing (different regions) → Heatmap overlay → Build composite best-of-both per LBA; fill gaps from whichever reads clean.

3. Heads stuck (stiction) → Acoustic/spin → Free HGA or swap; cold low-speed imaging; mirror reconciliation.

4. Spindle/motor seized → Current ramp → Motor/chassis transplant; servo align; image → reconcile.

5. Preamp failure → Bias anomaly → HSA swap; conservative imaging; compare with peer.

6. Platter rings/scratches → Zone error map → Skip-range multipass; rely on good mirror where available.

7. Translator corruption (0-LBA) → Vendor fix; image; pair with peer to restore full set.

8. G-list explosion (“slow issue”) → Disable BG ops → Head-zoned imaging; prefer peer where faster.

9. SMR slowdowns → Timeout budgeting → Zone-aware imaging; merge with peer.

10. Helium leak instability → Temperature sweet-spot passes; majority selection vs peer.

11. SATA connector cracked → Rework/link-clamp; image; compare.

12. Backplane CRC storms → New HBA/cables; QD=1 imaging; reconcile.

13. NVMe controller resets → Clamp link (Gen3 x1/x2), active cooling; burst read; compose with peer.

14. NVMe 0-capacity / lost namespace → Admin path export; else chip-off + FTL; merge with peer.

15. SSD controller dead → Loader export or chip-off; FTL rebuild; prefer intact mirror if peer OK.

16. SSD NAND retention loss → Cold imaging, voltage stepping; page-vote merge; prefer peer.

17. SSD RO-lock → RO image within window; use peer for bad ranges.

18. Different sector sizes 512e/4Kn → Detect & normalise sizes before mirror compose.

19. HPA/DCO hidden LBAs on a member → Remove on clone; align to peer; assemble.

20. Encryption at device level (SED/Opal) → Keys required; decrypt clone(s) first; then mirror compose.

Controller/HBA/cache & metadata — 21–35

21. Controller failure → No import → Clone members; software-model mirror; repair FS.

22. BBU/cache loss (write-back) → Torn writes → Journal-first FS repair; prefer blocks validating against journal.

23. Foreign config mismatch → NVRAM vs on-disk → Use on-disk metadata; ignore stale controller state.

24. Firmware bug altered geometry → LBA translator change → Correct mapping layer; compose mirror.

25. Hot-spare promoted incorrectly → Stale/empty copy → Exclude poisoned member; use good epoch.

26. Write-ordering drift → Cache policy change → Decide authoritative member by journal coherence & timestamps.

27. Metadata cached/not flushed → Divergent superblocks → Epoch voting; pick coherent set; copy-out.

28. Background patrol read rewrote sectors → Reallocation divergence → Prefer member with earlier healthy sectors.

29. Controller marks good disk “failed” → Validate by raw reads; include good actor.

30. Mirror bitmap corruption → Desync flags wrong → Ignore bitmap; do content-based comparison.

Array administration mistakes — 36–50

31. Wrong disk replaced → Removed good member → Re-include correct one from clone; discard new blank.

32. Accidental reinitialise → Fresh mirror started → Keep pre-init member; block-wise salvage from other if any.

33. Rebuild to failing disk → Contamination → Use pre-rebuild clone; ignore rebuild writes.

34. Swap order in NAS slots → Metadata confusion → Identify by WWN/serial; reattach logically.

35. Forced sync on degraded set → Propagated errors → Roll back to earliest good clone; compose.

36. Online capacity expansion aborted → Partial mirror extension → Treat extended tail separately; mount pre-OCE epoch.

37. Converted to RAID 0/5 by mistake → New layout wrote headers → Ignore new config; raw compose legacy mirror.

38. Auto-repair after power loss → Divergent heads → Choose member matching journal; block-wise fixups.

39. Multiple hot-swap events → Slot/UUID drift → Map by serial/WWN; rebuild mirror view.

40. Write-intent bitmap stale → Rebuild skipped → Full compare; resync virtually on image.

RAID 1-specific divergence scenarios — 51–70

41. Silent divergence (no alarms) → Years of mismatch → Block-hash walk across both clones; select by FS validity & timestamps.

42. Half-written files (write hole) → One member completed, one not → Prefer journal-consistent member; salvage partial from other only if needed.

43. NTFS journal present only on one → Pick journal-coherent copy; replay log; export.

44. APFS checkpoint differs across members → Choose coherent checkpoint; discard later poisoned writes.

45. ReFS integrity streams disagree → Use checksum-valid copy; log exceptions.

46. XFS log mismatch → Manual log replay on coherent member; dir rebuild.

47. ext4 dirty bit differs → Use backup superblocks; choose member with consistent inode tables.

48. Btrfs mirror with scrub divergence → Checksum voting across mirrors; export snapshot.

49. ZFS mirror with one bad leaf → zpool import -o readonly -f -T <txg> on image; scrub; export datasets.

50. Boot sectors differ → Don’t “repair” originals; mount data from consistent member on clone.

Filesystem/LUN on top of the mirror — 71–88

51. GPT/MBR wiped on one member → Synthetic GPT from FS headers; prefer intact map.

52. Quick format on one side → Headers overwritten → Use other member; deep-carve remnants from formatted side if needed.

53. Full format on one side → Overwrite → Salvage entirely from unformatted member.

54. BitLocker over mirror → One member partially encrypted → Use pre-encrypt member; or decrypt both with recovery key then compose.

55. FileVault/LUKS over mirror → Credentials needed → Unlock on image; choose volume with intact header.

56. VMFS datastore mismatch → Header only on one → Rebuild from headered member; restore VMDK chains.

57. iSCSI LUN file only on one side → Carve LUN; mount guest FS; export.

58. Sparsebundle (Time Machine) damaged on one → Use other; repair bands; enumerate snapshots.

59. Large media fragmentation → Range-map reconstruction; GOP-aware stitching; prefer intact member for keyframes.

60. Database torn pages → Page-level salvage from coherent member; redo/undo logs.

Interface/bridge/backplane quirks — 89–95

61. USB/TB bridge encrypts one path → Hidden hardware crypto → Unlock/password (if known) then image; or transplant to plain bridge.

62. UASP driver bug hits only one → Force BOT/QD=1; image; compose.

63. Mini-SAS cabling fault → One link error-prone → Direct HBA attach; image; compare.

64. 4Kn translation in one enclosure → Sector size lies → Present native size in model; align.

65. SMART passthrough blocked → No health → Attach bare drive to read SMART & plan imaging order.

Environmental / power / handling — 96–100

66. Overheating NAS → Thermal throttling → Active cooling; prioritised imaging; compose.

67. Power surge/outage → Simultaneous faults → Electronics repair + imaging on both; pick coherent epoch.

68. Fresh-water ingress → Neutralise/dry; do not power; triage electronics/mechanics; image both.

69. Salt-water ingress → Immediate neutralisation; accelerated imaging window; compose best-of.

70. Shock/vibration → Head slap on one → HSA swap; rely on healthy peer for affected ranges.

Human/operational pitfalls — 71–100

71. Ran chkdsk/fsck on failing mirror → Secondary damage → Roll back to pre-repair clones; journal-aware rebuild.

72. Mounted RW for “quick copy” → New writes contaminate → Ignore post-incident writes; use earlier coherent member.

73. Attempted sector-by-sector clone to peer → Clobbered good data → Use earlier backups; carve remnants.

74. TRIM enabled on SSD mirror → Deleted data purged on both → Focus on app journals/caches; set expectations.

75. Ransomware encrypted only one member first → Divergence window → Salvage from unencrypted member; then decrypt where feasible.

76. Antivirus quarantined DBs on one side → App failure → Use intact mirror; repair DB.

77. Mixed firmware revisions → Behaviour drift → Prefer stable revision; verify with FS checks.

78. Non-ECC RAM parity scrub corruption → Silent flips → Validate with filesystem checksums/hashes; select clean blocks.

79. Disk serials mis-labelled → Member identity confusion → Map by WWN/serial; correct order.

80. NAS auto-rebuild after wrong disk swap → Poisoned copy → Revert to pre-rebuild clone; exclude poisoned ranges.

81. Controller bitmap flagged “in-sync” incorrectly → Skipped resync → Full block compare; resync virtually.

82. Async replication mistaken for RAID 1 → Not a mirror → Treat as backup/replica; recover newest consistent side.

83. Write-back cache without BBU → Lost writes → Journal-first; accept some torn files.

84. Disk firmware “slow issue” → Disables mirror check → Image with tuned timeouts; content-compare.

85. Drive with hidden HPA used as mirror → Off-by-cap → Remove HPA on clone; align to peer.

86. USB power-only mirror (dual docks) → Under-power resets → Bench PSU; stable imaging.

87. Mixed 4Kn & 512e members → Misalignment → Logical normalisation; compose.

88. De-dup appliance mistaken for mirror → Hash store, not RAID → Rehydrate via hash map; export.

89. DFSR/roaming profiles confused with mirror → Staging/Conflict folders → Mine staging for clean copies.

90. Snapshot-based “mirror” in NAS → Versioned copy → Export correct snapshot; ignore live divergence.

91. User zeroed first MB “to fix” → Header loss → Recreate partition map from FS signatures; mount.

92. Disk signature collision → OS mounts wrong → Assign new signature on clone; RO mount.

93. Hybrid HDD+SSD mirrored pair → Latency mismatch → Image independently; compose by block quality.

94. Bit rot over years (no scrubs) → Silent corruption → Prefer member with consistent checksums/journals.

95. Filesystem case-sensitivity mismatch (APFS) → Name conflicts → Normalise on export; preserve metadata.

96. VMFS heartbeats on only one → Host recovered partly → Restore VMs from that member; verify.

97. LUKS header corrupt on one → Use backup header from peer; decrypt; export.

98. FileVault keybag intact only on one → Use that member to unlock; replicate to composed image.

99. RAID assistant metadata stale (macOS) → Rebuild from on-disk; prefer coherent member.

100. “Repair tools” wrote new metadata → Secondary overwrites → Use pre-tool clones; ignore later writes.

Why choose Plymouth Data Recovery

• 25 years of RAID recoveries across NAS, servers and DAS

• Forensic-first workflow (clone originals, virtual reassembly, RO exports)

• Advanced tooling & donor inventory (controllers, HBAs, heads, PCBs)

• Clear, free diagnostics before any paid work begins

Talk to a RAID 1 engineer

Contact Plymouth Data Recovery today for your free diagnostic. We’ll stabilise the members, reconstruct the mirror virtually, and recover your data with forensic-grade care.