After opening the drive, we identified the cause of failure – the read/write heads remained stuck on the data platters instead of the parking zone. This can happen for various reasons, but here it was most likely the result of a drop or impact.
Complications During Head Release
The situation was worse than it initially appeared. When attempting to release the heads, two sliders completely detached from the suspension arms. A slider is a ceramic carrier holding the actual read/write elements – its detachment means the heads are completely destroyed and there's also a risk of damage to the data platters. In this case, one slider remained lying directly on the platter surface.
We completely disassembled the drive. We carefully removed the slider and thoroughly cleaned both platters. Microscope inspection showed acceptable condition – no scratches or other damage indicating head contact with the platter surface during rotation. The damage occurred outside the area containing user and service data.
Head Transplant from a Compatible Drive
To recover data from a drive with damaged heads, we need to find a suitable donor – a functional drive of the same type from which heads can be transplanted. It's not just about having the same drive model. Head compatibility for Western Digital depends on matching several parameters: firmware revision, number of heads and platters, and not least the production series. Two drives of the same model manufactured in different factories or several months apart may have different heads that are not interchangeable.
After installing the new magnetic heads and reassembling the drive, the mechanics successfully spun up. The drive was detected by the system and responded to ATA commands – we could proceed with reading.
Why Specialized Tools Are Essential
Reading such damaged drives requires professional tools, in our case PC-3000 Express. A regular computer wouldn't handle such a drive for several reasons.
A standard SATA controller in a computer expects the drive to respond to every request within milliseconds. If the drive doesn't respond in time, the controller marks it as faulty and disconnects it. However, a damaged drive with replaced heads often needs several seconds to read a single sector – a regular system would repeatedly disconnect and reconnect it, only making the situation worse.
PC-3000 Express provides full control over communication with the drive. We can set arbitrary timeouts, skip problematic areas and return to them later, change reading modes on the fly, and most importantly – work directly with the drive's service data. All this without the risk of the operating system "pulling" the drive away mid-operation.
In the PC-3000 environment, we first backed up the service area containing firmware modules and adaptive parameters. The head map matched expectations – two platters, four heads. Reading proceeded with expected complications because replacement magnetic heads never perform as well as the originals. Each set of heads is individually calibrated at the factory for specific platters, and these adaptive parameters are stored in the drive's firmware. With different heads, we read without these optimizations, which means more errors and slower progress.
We used various reading modes including speed adjustments and other service data modifications. The process took several days, but we managed to read the complete drive contents.
Drive: WD Scorpio Blue WD5000BEVT-00A05T0
Capacity: 500 GB
Problem: Heads stuck on platters, broken sliders
Solution: Complete disassembly, platter cleaning, head transplant from compatible donor
Result: Complete binary copy, successful file system analysis
Summary and Recommendations
Heads stuck on platters are a serious problem, but not necessarily fatal. The key is not to attempt repeated drive startups – each attempt to spin up with heads on the platters increases the risk of irreversible damage. Broken sliders complicate the situation, but as long as the platters remain undamaged, the chance for data recovery exists. If you encounter a similar problem, it's better to hand the drive over to a specialized facility.
Glossary
Read/Write Heads – miniature electromagnetic components that float just above the surface of rotating data platters and read or write data. The distance between the head and platter is smaller than the thickness of a human hair. When the drive powers down, the heads park in a safe zone outside the data area to prevent contact with the surface.
Slider – a ceramic carrier on which the actual read/write element is mounted. The slider has an aerodynamic shape that ensures the head floats at a stable height during platter rotation. If the slider detaches from the suspension arm, the head is destroyed and there's a risk of platter surface damage from loose fragments.
Service Data (Service Area) – a dedicated area on the data platters where the drive stores its firmware, calibration parameters, defect tables, and other operational information. Without access to service data, the drive won't function even if it's mechanically sound. Professional tools allow backing up, modifying, and if necessary restoring service data.
- Details
- By Frantisek Fridrich
- Parent Category: Blog
- From Practice
