HP & QNAP Raid Recovery

Case Study: QNAP RAID 5 Failure After Drive Replacement – 4 WD Disks

Background

A small business owner in Nottingham encountered a severe RAID failure while attempting to replace a failing hard drive in their QNAP RAID 5 NAS, which contained four WD disks.

  • The system initially reported one disk failure (indicated by a red light).
  • The user removed the failed disk and installed a new drive into the array.
  • The system started a RAID rebuild, but marked the entire RAID array as failed instead.
  • After multiple unsuccessful rebuild attempts, the RAID 5 array remained inaccessible, and all business documents, company plans, and important images stored on the NAS were lost.

With the QNAP RAID 5 array failing to rebuild, the client contacted Nottingham Data Recovery, Nottingham’s best data recovery company, with 25 years of experience in professional RAID data recovery.

The Problem

Upon analysis, the following issues were identified:

  1. Incorrect RAID Synchronisation During Rebuild
    • When the failed drive was removed and replaced, the NAS began a RAID rebuild with incorrect parity calculations.
    • This resulted in the entire RAID array being marked as failed.
  2. RAID Metadata Corruption
    • The QNAP RAID controller overwrote metadata, making the array unreadable.
    • The new disk was not recognized as part of the original RAID structure, making the existing data inaccessible.
  3. Multiple Failed Rebuild Attempts Further Damaged the Data
    • Each attempted rebuild further corrupted RAID parity data.
    • The user was unable to access the drives to extract files before the rebuild started.
  4. No Backup Available
    • The business had no recent backup, making recovery essential.

The Data Recovery Process by Nottingham Data Recovery

Step 1: Initial Assessment

The recovery team performed a comprehensive evaluation:

  • Physical Health Check:
    • All four RAID 5 disks were examined individually.
    • The originally failed drive was completely non-functional, but the other three contained recoverable data.
  • Logical RAID Analysis:
    • RAID metadata was partially overwritten due to failed rebuild attempts.
    • The new disk was excluded from further operations to avoid additional corruption.
  • Filesystem & Partition Scan:
    • The file system was corrupted due to the RAID controller failing to recognize the correct parity layout.

Step 2: RAID 5 Virtual Reconstruction

1️⃣ Sector-by-Sector Cloning

  • Each of the three working RAID disks was cloned to prevent further damage.
  • The bad sectors from the degraded drives were bypassed using advanced recovery tools.

2️⃣ RAID 5 Array Reconstruction

  • Using proprietary software, the original RAID 5 stripe size, disk order, and parity rotation were reconstructed manually.
  • The overwritten RAID metadata was restored, allowing access to the missing files.

3️⃣ File System Repair & Recovery

  • The EXT4 file system used by QNAP NAS devices was manually repaired.
  • Missing file structures were rebuilt, restoring business plans, documents, and images.

Step 3: Data Extraction & Verification

✅ File Integrity Testing

  • The business documents, images, and company records were extracted and tested for corruption.
  • All files were validated for usability before being returned to the client.

✅ Secure Data Transfer

  • The recovered data was securely transferred to a new external NAS system.

Challenges Faced

  1. RAID Metadata Corruption
    • Since the NAS overwrote metadata, the RAID structure had to be rebuilt manually.
  2. Multiple Failed Rebuild Attempts
    • Every attempted rebuild worsened the RAID corruption, requiring advanced techniques to reconstruct the data.
  3. File System Corruption
    • The EXT4 file system had suffered directory loss, requiring manual reconstruction.

Outcome

✅ Recovered 99% of the business-critical files, including documents and images.
✅ Delivered the recovered data within 72 hours, allowing the company to resume operations.
✅ Advised the client on best RAID 5 management practices to prevent future failures.

Lessons Learned

  1. Avoid Immediate RAID Rebuilds
    • Always back up data before replacing a failed RAID drive.
  2. Monitor RAID Health with Alerts
    • Use RAID monitoring tools to detect degraded drives early.
  3. Seek Professional Help Before Attempting a Rebuild
    • DIY RAID rebuild attempts can overwrite metadata and cause permanent data loss.

Why Choose Nottingham Data Recovery?

✅ 25 Years of Experience in handling RAID failures and NAS recovery.
✅ Advanced RAID 5 Reconstruction Tools to restore damaged arrays.
✅ Fast & Secure Recovery ensuring minimal downtime for businesses.
✅ Expert Guidance on best RAID maintenance practices.

This case highlights Nottingham Data Recovery’s expertise in QNAP RAID 5 failure recovery, ensuring the business was able to recover all critical files and continue operations without disruption.