Case Study
Successfully Recovered Data from Crashed Dell® RAID 5 Storage Server
Business downtime led to hampered decision-making, potential revenue loss, and the risk of permanent data loss.
Business Challenge
The organization is a large travel company with presence in Europe, the USA, Russia, and Asia Pacific. It provides business travel, outbound tourism, holidays, destination management, and other such services in the travel domain.
It was using a Dell® storage server which comprised of 4*2TB Serial Attached SCSI (SAS) Hard Disk Drives stacked up as a RAID configuration. The server was hosting about 2.5 TB data which largely included crucial business information in the form of accounting data, banking data, images, and various other documents.
Situation Overview
One of the disks in the RAID configuration was detected in a failed state which explained the marked degradation in performance of the server; the server read/write speeds had become very slow, with frequent freeze ups.
The Dell PowerEdge RAID Controller (PERC) card attempted rebuilding the failed physical disk by using the pre-configured hot spare, however, the auto-replacement mechanism didn’t succeed for an unaccounted reason.
Subsequently, the storage server administrator decided to take the manual restoration route via the CONTROLLER BIOS Configuration Utility – he replaced the failed disk with a compatible new physical disk of 2 TB capacity; however, the array disks still appeared in a degraded state even after reseating the hot swap, running system diagnostics, etc.
In the meanwhile, due to the continuous usage of this degraded RAID setup with no redundancy, the storage server crashed. Subsequently, the server failed to boot up and displayed the message – “No boot device found”.
Failure of the Dell® storage server turned the complete 2.5 TB data inaccessible, with a high probability of permanent data loss unless the storage could be revived to an accessible state so as to allow data recovery operations.
Business Impact
As the server was used for hosting business-critical assets, its failure affected the overall business, as the stakeholders were unable to access key data points for decision making.
Also, the data on the server largely comprised of banking and accounting information, so its unavailability hampered a majority of business transactions.
Solution — How Stellar® Data Care Experts Rescued the Situation?
After attempting to revive the RAID server by following the standard disk replacement procedures, the IT team of the company decided to engage Stellar® Data Recovery services.
Stellar® - on account of its experienced R&D team, broad expertise in dealing with RAID failure cases, and Class 100 cleanroom infrastructure - was uniquely positioned to deliver the best possible solution for this situation.
Solution Approach
Stellar® put together a dedicated team of R&D engineers and data care experts to execute this project. This team began the data recovery task as per the following steps:
- Lab examination of Dell ® Storage Server
- The team examined all the 4 hard disk drives on logical and physical aspects to ascertain their functional state (working/non-working). It was found that 3 of the hard drives had physical problem (clicking sound) and the remaining 1 hard drive was working properly.
- Physical problems with multiple hard drives (including one failed hard drive) was found as the cause of RAID failure that had resulted in the server crash and data inaccessibility.
- Hard drive dismantling and head assembly replacement in state-of-the-art Class 100 cleanroom
- The team sought tampering permission from the client organization to open up and check the physical condition of the platter and head assembly of the 3 affected hard drives.
- The head assembly inside all these affected drives was found as broken or dysfunctional.
- Further, there were light visible scratches on both sides of the four platters in one of drives, whereas another drive had light scratches on one of its platters. This finding would affect the prospects of getting complete recovery of data from these drives.
- Nonetheless, the team went ahead and transplanted new head assemblies on each of the 3 hard drives to practically evaluate the possibilities of disk cloning and data recovery.
- Disk cloning and process to determine RAID configuration parameters
- The data care experts cloned the recoverable hard drives by using a proprietary disk cloning software.
- It got access of 2 of the hard drives and created clones of the same. One of these hard drives could be partially cloned due to light scratches on one of its platters.
- Cloning of the 3rd hard drive couldn’t be done due to scratches on both sides of its four platters. The data stored on this drive was irretrievably lost.
- The 4th hard drive was cloned successfully.
- Next, the R&D team connected these 3 cloned hard drives to a specialized server for gaining access to the individual drives. This was necessary for determining key RAID array logical parameters viz. strip size, data flow pattern, RAID configuration, and parity flow information.
- Upon byte-wise examination of these 3 individual drives, the team found NTFS file system structure with RAID 5 configured in this Dell® storage server.
- The data care experts cloned the recoverable hard drives by using a proprietary disk cloning software.
- Deep scanning to retrieve data
- The data care experts used Stellar® data recovery software with file signature based deep scanning function on this single clone to recover data.
- The team successfully recovered the lost data from the crashed Dell® storage server.
Result
The Stellar® data recovery services team successfully recovered the lost data from the Dell® storage server. The entire data recovery project — from job intake and allocation to execution and final recovery — was completed and delivered within the committed time.
The data was recovered with 100% integrity in its original form, as verified and attested by the client. This remarkably fast turnaround and service quality helped the client organization to quickly recover from downtime and resume normal business.
Statement from the customer:
"Stellar successfully recovered lost data, ensuring 100% integrity throughout the process"
Travel Company
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