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RAID 6 Recovery – Research Institution Data Preservation

We are thrilled to share a recent success story showcasing our expertise in data recovery. Our commitment to excellence and advanced technology allowed us to successfully recover critical data for one of our valued clients.

Client Information:

  • Industry: Scientific Research
  • Location: Boulder, Colorado
  • Array Config: RAID 6 (8x 12TB Enterprise SATA HDDs)
  • Total Capacity: 96TB (72TB usable)
  • Use Case: Climate modeling and environmental datasets
System Specifications:

The client operated a critical database server housing sensitive financial data with the following configuration:

  • Storage: Synology RS4021xs+
  • RAID Controller: Synology DiskStation Manager with hardware-accelerated RAID
  • Storage Devices: 8x Western Digital Ultrastar DC HC520 12TB Enterprise HDDs
  • File System: Btrfs with data integrity checking and snapshot capabilities
Failure Incident:

Failure Scenario: During a severe thunderstorm in January 2025, the research facility experienced multiple power fluctuations despite having UPS protection. The storage system suffered a cascading failure that affected multiple drives simultaneously. The situation became critical when a third drive began showing signs of potential failure. While RAID 6 can handle two drive failures without data loss, a third drive failure would exceed the array’s fault tolerance and result in complete data loss. The timing was particularly concerning as the institute was preparing to submit critical climate data to an international research consortium, with a deadline just one week away. The array contained:

  • 45.2TB of historical climate datasets (irreplaceable)
  • 18.7TB of current research projects and analysis
  • 5.8TB of climate model simulation results
  • 2.3TB of collaborative research data from partner institutions
Technical Analysis:
Our emergency response team’s assessment revealed a complex scenario where the RAID 6 array was operating normally with two failed drives but faced the imminent threat of a third drive failure that would exceed its fault tolerance:
Drive Status Assessment:
  • Drive 1 (Bay 1): Fully functional with clean SMART status
  • Drive 2 (Bay 2): Complete controller failure, no response to interface commands
  • Drive 3 (Bay 3): Fully functional with clean SMART status
  • Drive 4 (Bay 4): Showing early warning signs – increasing read retry counts and temperature fluctuations
  • Drive 5 (Bay 5): Fully functional with clean SMART status
  • Drive 6 (Bay 6): Head crash failure with extensive platter damage
  • Drive 7 (Bay 7): Fully functional with clean SMART status
  • Drive 8 (Bay 8): Fully functional with clean SMART status

RAID 6 Parity Analysis: The Synology system implemented Reed-Solomon error correction with dual parity (P and Q parity) distributed across all drives. Our analysis confirmed that the dual parity system could theoretically recover from the two-drive failure, but the physical damage to both failed drives presented significant challenges.

Data Distribution Impact: With 2MB stripe sizes, large climate datasets were distributed across all eight drives. The loss of two drives meant that approximately 25% of each large file’s data blocks were missing and would need to be reconstructed using the dual parity information.
Recovery Methodology:

Phase 1: RAID 6 Dual Parity Recovery Strategy

Drive 2 Controller Repair: The Western Digital Ultrastar drive’s controller board had suffered power surge damage. Our hardware team sourced an identical controller board and performed a firmware transfer to enable data access.
Drive 6 Assessment: The head crash damage with extensive platter scoring made this drive unrecoverable. Rather than attempting risky cleanroom procedures that could potentially damage other components or delay recovery, we leveraged RAID 6’s dual parity capability to reconstruct all data from the remaining healthy drives.
RAID 6 Parity Utilization: With six healthy drives remaining in the 8-drive array, the dual parity system had sufficient redundancy to reconstruct all data that was stored on the two failed drives without any physical recovery attempts.

Phase 2: Dual Parity Reconstruction

Reed-Solomon Implementation: We developed specialized software to implement the Synology RAID 6 Reed-Solomon algorithm, allowing us to reconstruct missing data blocks using the P and Q parity information from the six functional drives.

Stripe-Level Recovery: For each 2MB stripe across the array, we calculated the missing data from Drives 2 and 6 using the mathematical relationships defined by the dual parity system:
  • P parity: Simple XOR of all data blocks in the stripe
  • Q parity: Reed-Solomon polynomial calculation across all blocks
Error Correction Validation: Each reconstructed block was validated using multiple methods:
  • Btrfs filesystem checksums where available
  • File format validation for known data types
  • Cross-reference with partial data recovered from damaged drives

Phase 3: Scientific Data Validation

The data was checked and validated in collaboration with climate scientists.

Phase 4: Priority-Based Recovery
Given the research deadline, we implemented a tiered recovery approach:
  • Tier 1 – Consortium Submission Data: The 12TB of climate datasets required for the international submission were prioritized for immediate recovery.
  • Tier 2 – Active Research Projects: Current analysis and modeling data needed by research teams were recovered next.
  • Tier 3 – Historical Archives: Long-term climate records were recovered systematically to ensure complete data preservation.

Recovery Results

Data Recovery Success Rate: 99.6% (71.712TB of 72TB recovered)
Critical Research Data: 100% recovery of consortium submission datasets
Historical Climate Records: 99.8% recovery of irreplaceable historical data
Recovery Timeline: 48 hours for critical data, 168 hours for complete recovery
Research Impact: None
Unrecoverable Data Analysis: The 0.4% of unrecoverable data consisted of:

  • Temporary processing files from climate modeling software
  • Cached visualization data that could be regenerated
  • Some duplicate backup files (original data was recovered)

Client Impact:

The successful recovery had critical implications for climate research:
International Collaboration: The institute met its deadline for the international climate consortium, contributing essential data to global climate modeling efforts.
Research Continuity: All active research projects continued without interruption, preserving months of analysis work and computational modeling.
Data Preservation: Irreplaceable historical climate data spanning 40+ years was preserved for future research and climate trend analysis.
Scientific Credibility: The institute maintained its reputation as a reliable data provider for the international climate research community.

Lost Data on Your Storage Device? Act Immediately!

If your are experiencing data loss, DO NOT attempt to force-rebuild RAID, reinitialize drives, or operate the system, as this can lead to irreversible data loss. Power down the device(s) immediately and keep the drives in their original slots/order. Contact our experts.

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