PDR Survey: An Inside Look at the Causes of Hard Drive Failure

15 Dec 2011

Between 2007 and 2010, we conducted a study with some of our largest clients. 55 data recovery companies in 15 different countries participated in this survey. We found the results to be quite valuable and wanted to share them with you, along with some of our notes.

What problems occur in hard drives sent in for recovery?
(Drives usually have more than one issue that needs to be resolved during the recovery process. For example, head failure, PCB failure and media problems could all occur at once.)
% Our Notes
Head stack failure (failed heads/preamp): 23.50%  
Disk platters scratch: 6.70%  
Motor seizure: 5.80%  
Heads stuck to disk platters: 6.40%  
Other physical/mechanical issue: 8.00%  
PCB failure (electronic issue): 16.10%  
Firmware failure, such as translator corruption: 17.50%  
Read instability issues, that is, cases when a drive occasionally becomes unresponsive, responds very slowly, makes occasional clicks while executing certain commands, has a failure of one of its non-critical subsystems (such as SMART) or has other degradation factors: 22.00%  
Reading media problems (bad sectors): 37.50% Disk-level problems are the most common issue.
File system structure corruption: 26.20% Most of the corruption here is caused by bad sectors, so the first thing to do in these cases is to retry retrieving more data during imaging.
User files corruption: 19.40%

What causes initial data loss? % Our Notes
Drive failure (drive doesn't respond at all): 38.00% These are drive-level issues/causes (dealt with by using Phase I tools).
Drive read instability problems, such as the drive being incorrectly identified or unidentified by BIOS due to issues with some of its subsystems, it stops responding occasionally, has bad sectors, etc.: 29.90% These are disk-level issues/causes (dealt with by using Phase II tools).
Software issue, for example, OS crash, virus attack: 12.80% These are data-level issues/causes (dealt with by using Phase III tools).
User error, such as accidentally deleted files, reformatted partition: 12.10%
Lost password and other file system security issues: 5.50%
Other cause: 1.70%  

What makes cases unrecoverable? % Our Notes
Unidentified/unknown nature of the problem: 5.10%  
Lack of technology/tools, such as those needed to access firmware, to swap a motor or multi-disk assembly, to repair files: 19.50%  
Previous unprofessional recovery attempts: 13.30% These are cases when someone who doesn’t have professional tools/expertise already tried to fix the drive or recover the data. As we can see, this figure is rather high.
Irreparable physical/mechanical damage, such as disk platters scratch: 20.70%  
Irretrievable firmware damage, such as lost adaptives or PList: 5.60%  
Irretrievable file system damage, such as lost FAT or directory entries, corrupted file: 5.20% We believe this number would be lower if better disk imaging methods were used. Fewer files would be corrupted.
Inability to find physical/electronic donor parts: 7.80%  
Inability to find compatible firmware (to fix SA/ROM damage): 4.10%  
Reading media instabilities (too many bad sectors): 8.20% Again, this number would be lower with better disk imaging methods.
Excessive time required to complete recovery process, for example, long imaging, requirements to fix an issue too many times during imaging: 5.70% This number could also be lower, especially if imaging is done by files instead of imaging the entire drive.
Drive irretrievably failed during recovery process, for example, due to degradation of parts: 4.00%  
Other cause: 0.90%  


You can read more about some of these problems, along with their diagnostics and recovery procedures, at How to Diagnose and Recover the Most Common Cases