Case Study: Critical Recovery from a DELL PowerEdge 2600 RAID 5 Array Following Controller Configuration Corruption
Client Profile: User of a DELL PowerEdge 2600 server with a 3-disk RAID 5 array.
Presenting Issue: Catastrophic array failure and server unbootability after attaching an external bootable drive. The RAID controller reports the array as offline or missing, with all data inaccessible.
The Fault Analysis
The client’s action of introducing an external bootable drive likely caused a conflict with the existing RAID controller’s configuration, stored in its NVRAM. The DELL PowerEdge 2600 typically uses a PERC (PowerEdge Expandable RAID Controller) series card. These controllers are highly sensitive to their boot order and configuration integrity.
Our diagnosis pointed to one of two specific failure scenarios:
Configuration Metadata Corruption: The introduction of the new drive may have caused the controller to re-initialize its configuration, overwriting the critical metadata that defined the RAID 5 array’s parameters (disk order, stripe size, parity rotation algorithm, and start data offset). The array’s data remained intact on the physical drives, but the “map” to reassemble it was lost.
Boot Priority Conflict and Partial Rebuild Initiation: If the controller mistakenly tried to boot from the new drive or treated it as a member of the array, it may have attempted an incorrect rebuild or consistency check, leading to the corruption of the parity data across the stripes. This would render the entire logical volume inaccessible.
The server’s failure to boot and the subsequent dropping of the data disks from the controller’s BIOS are clear indicators of a corrupted volatile configuration on the controller itself.
The Bracknell Data Recovery Solution
Recovering from this scenario required a forensically sound approach that completely bypassed the original, faulty RAID controller to manually reconstruct the array in software.
Phase 1: Physical Drive Stabilisation and Forensic Imaging
Each of the three hard drives from the array was carefully removed from the server and labelled according to their original bay positions.
Individual Drive Diagnostics: Each drive was connected to our PC-3000 system and DeepSpar Disk Imager for individual sector-level diagnostics. This step was critical to rule out concurrent physical media failure on any single drive, which would have compounded the logical corruption.
Sector-Level Imaging: We created full, bit-for-bit forensic images of all three drives onto our secure recovery storage. This process ensured all subsequent recovery work was performed on the images, preserving the original drives in their exact state. The imaging logs confirmed all three drives were physically healthy, confirming the issue was purely controller-configuration based.
Phase 2: RAID Parameter Analysis and Virtual Reconstruction
With the three disk images, the core task of reverse-engineering the original RAID parameters began.
Stripe Size and Order Determination: Using our proprietary software, we performed a block analysis across all three images, searching for repetitive data patterns and parity blocks. By analysing the cyclic redundancy of data and parity across the drives, we empirically determined the stripe size (e.g., 64KB, 128KB) and the disk order (which physical drive was the first member of the array). An incorrect disk order would result in nonsensical data.
Parity Rotation and Direction Identification: RAID 5 can use different parity rotation schemes (left-asymmetric, right-asymmetric, etc.). We tested these algorithms against the imaged data, looking for a configuration where the calculated parity (using a XOR operation across the corresponding blocks in the stripe) matched the stored parity on the designated drive. This confirmed the parity rotation algorithm and the data direction.
File System Header Validation: Once a potential set of parameters was assembled, we built a virtual RAID 5 in our software. We then checked the start of this virtual volume for a valid NTFS Boot Sector (
EB 52 90 4E 54 46 53). A valid boot sector confirmed we had correctly identified the start data offset and all other parameters.
Phase 3: Logical Volume Assembly and Data Extraction
After successfully defining the virtual RAID, our software seamlessly assembled the disk images into a single, coherent logical volume.
File System Traversal: We mounted the virtual volume and traversed the Master File Table (MFT) of the NTFS file system. The MFT was found to be entirely intact, as the physical drives had not suffered any data loss; only the controller’s “map” was lost.
Data Integrity Verification: We performed checksum verification on a sample of recovered files, confirming that the data and file structure were perfectly reconstructed. The client’s folder structure for each computer was fully restored.
Conclusion
The data loss was caused by a corruption of the RAID controller’s volatile configuration metadata, triggered by a hardware addition. The controller lost the instructions to properly assemble the RAID 5 set, rendering the perfectly healthy physical drives unreadable as a group. Our recovery success was contingent on completely bypassing the failed hardware controller, using forensic analysis to manually deduce its original configuration, and then reconstructing the array virtually in software.
The recovery was executed with 100% success, restoring the entire multi-folder directory structure and all client data from the failed array.
Bracknell Data Recovery – 25 Years of Technical Excellence
When your complex storage system like RAID fails due to controller error or configuration corruption, trust the UK’s No.1 HDD and SSD recovery specialists. We possess the specialised knowledge and tools to manually reconstruct and recover data from the most challenging multi-disk scenarios.