Donor Drive

In professional data recovery, the failed drive that holds the customer’s data is called the patient or the original. The healthy drive used to supply replacement parts is called the donor. The donor’s job is to give up its working components so the patient drive can run long enough to be imaged to a healthy destination drive.¹ Once the imaging is complete, the patient drive is no longer needed, and the donor has typically been consumed in the process.

When donors are needed

Donor drives are required for any physical recovery where a hard drive component must be replaced:

• Head crashes: failed heads need transplant from a donor’s head stack assembly.
• Click of death from head failure: when clicking is caused by failed heads, the heads need replacement.
• Failed PCBs: the printed circuit board on the underside of the drive can fail from power surge or other electrical damage; replacement requires a compatible donor PCB plus ROM transfer.
• Pre-amp failures: the small amplifier on the head stack that boosts head signals can fail; donor parts may be needed.
• Stiction recovery: when heads stick to the platter, sometimes a fresh head stack from a donor is the cleanest path.
• Motor or bearing failures: rare scenarios where the drive’s spindle motor or bearings fail; in some cases the platters can be transferred to a donor’s working chassis.

When donors are NOT needed

Donor drives have a specific role; many recovery scenarios don’t involve them at all:

• Logical recovery (deleted files, formatted partitions, file system corruption) is purely software-based.
• Firmware corruption is fixed via specialized hardware tools like PC-3000 without physical donor parts.
• Bad sectors only are addressed via sector-by-sector cloning on the original drive.
• SSD recovery doesn’t use donor drives in the HDD sense; SSD parts replacement uses different techniques covered under chip-off recovery or board-level controller repair.

The destructive nature of donor recovery

Each physical recovery typically destroys the donor drive. The donor’s heads, PCB, or other parts are removed and installed in the patient. The donor cannot be reassembled and used again as a working drive. Recovery labs price donor cost into recovery quotes, and some quotes pass the donor cost through as a separate line item. For very rare drives where donors are scarce, the donor cost can dominate the total recovery price.

The most consistent finding in donor matching documentation: two drives sharing the same model number are often not interchangeable. Hard drive manufacturers produce the same model across multiple internal hardware revisions over the model’s production lifetime, and those revisions can have different head components, different preamp chips, and different firmware variations.²

A concrete example

The Rossmann Group documentation provides a specific case: a Seagate ST2000LM007 with firmware SBK2 from early 2017 and an ST2000LM007 with firmware SDM1 from 2020 are different hardware generations despite sharing a model number. The heads, preamp, and firmware are different. Using the SDM1 drive as a donor for the SBK2 patient will not work because the patient drive’s firmware expects specific electrical characteristics from the heads that the donor heads do not provide.³

This pattern repeats across manufacturers and models. Western Digital, Toshiba, Hitachi, and Samsung all produce the same model number across hardware revisions. Without deep matching, donor selection by model number alone produces incompatible donors more often than compatible ones.

Why the heads have to match precisely

Modern hard drives are manufactured with extremely tight tolerances. The heads are calibrated specifically for the platters they were paired with at the factory, with adaptive data stored in the drive’s firmware that compensates for tiny variations in head behavior. Donor heads from a different batch have different adaptive characteristics; using them produces one of three outcomes:

• The heads cannot read the data tracks written by the original heads; the recovery fails cleanly without further damage.
• The heads partially work but cannot precisely follow the data tracks; they scratch the platters as they attempt to read, destroying data permanently.
• The heads cannot fly properly above the platters at all due to mechanical incompatibility, leading to immediate head crash and platter damage.

The Datarecovery.com documentation captures the stakes plainly: at best a non-compatible donor produces a non-working recovery, and at worst it can permanently scratch the platters and destroy the data.⁴

Universal matching criteria

Across all manufacturers, several criteria typically need to match for a successful donor:

• Model number: exact match required for the first part; close match for the suffix.
• Firmware revision: the firmware controls signal timing, read channel calibration, and write current profiles. Different firmware = different expected head behavior.
• Heads map (physical heads): must be exact. Donor with extra heads is acceptable only if the patient drive supports them.
• Date of manufacture: within 3 months of the patient is the typical guidance; closer is better.
• Country of manufacture: usually must match because different factories use different manufacturing tolerances.
• Preamp vendor and revision: only obtainable via PC-3000 or similar tools.

Each major drive manufacturer has its own scheme for identifying drive variants. Recovery technicians need to know the specific matching codes for each manufacturer to source compatible donors reliably.⁵

Western Digital (DCM matching)

Western Digital drives use a Drive Configuration Matrix (DCM) code printed on the drive label. The DCM contains multiple characters that identify hardware variants. The matching technique:

• Locate the J or 2 in the DCM (typically toward the end of the value).
• The J or 2, plus the character preceding it, must match on the donor.
• Matching the four characters preceding the J or 2 further increases compatibility likelihood.
• Model number first part must match exactly; three characters of the second part (after the hyphen) must match.

Seagate (Site Code, Part Number, firmware)

Seagate drives carry a Part Number, Site Code, and Date of Manufacture on the label. The Site Code identifies the factory: WU for Wuxi, SU for Suzhou, TK for Thailand, and so on. Two Seagate drives with matching model numbers and firmware revisions but different Site Codes or Part Numbers may have incompatible head assemblies. Matching criteria:

• Model number: exact match.
• Firmware revision: exact match (four-character codes like CC26, SDM1, 0001).
• Site Code: match preferred, especially for older drives.
• Part Number: match preferred for tight compatibility.
• Date of Manufacture: within 3 months.

Toshiba (model, family, country)

Toshiba is generally considered the easiest manufacturer to source compatible donors for. The criteria:

• Complete model number: exact match (e.g., MK6026GAX).
• Family number: exact match (e.g., HDD2194 F ZE01 T).
• Country of manufacture: exact match (e.g., Philippines).

The first two are generally enough; matching the country adds final confidence.

Hitachi (model, part number, MLC)

Hitachi drives match on model + part number + MLC (Multi Level Cell) number:

• Full model number (e.g., IC25N04ATMR04-0).
• Part number (e.g., 0A30243).
• MLC number (e.g., DA2010).

For older Hitachi models (DK23-, DK13FA-, HTS series), matching schemes differ; recovery technicians consult model-specific guides.

The label’s color-coded priority system

Recovery labs use a priority system when matching label data:

Priority	Label data	What it controls
Essential (red)	Model number, family code	Basic hardware compatibility
High priority (orange)	DCM, Site Code, firmware	Internal revision matching
Medium (yellow)	Date of manufacture, country	Improves compatibility likelihood
Low (green)	Serial number, microjogs	Tiebreaker between candidates

Different physical failures require different donor parts. The most common transplants in increasing order of complexity:

Head stack assembly (most common)

The head stack assembly contains the read/write heads, the actuator arm that positions them, the voice coil that drives the actuator, and the connecting cables to the drive’s electronics. Failed heads are among the most common physical drive failures, and the heads are designed to be removable for manufacturing service. Engineers transplant a working head stack from a compatible donor into the failed drive’s chassis. The procedure happens in cleanroom conditions and takes a few hours of careful work. Once the patient drive responds with the new heads, immediate imaging captures the data before the rebuilt drive’s stability degrades.

PCB (printed circuit board) with ROM transfer

The PCB on the underside of the drive contains the controller chip, motor driver, and connecting traces. PCB failure can result from power surge, component degradation, or electrical damage. Modern PCB swaps cannot use the donor PCB directly; the original drive’s adaptive data lives on a small ROM chip on the PCB and is unique to that specific drive’s heads and platters.⁶

The procedure varies by drive model:

• For drives with a separate 8-pin ROM chip (typically labeled 25Pxx or 25Qxx), engineers desolder the chip from the dead PCB and transfer it to the donor PCB.
• For drives where the ROM is integrated into the controller chip (Marvell controllers, common in newer Western Digital drives), engineers use PC-3000’s WD module to read the ROM contents from the service area on the platters (which requires at least a partially functional original PCB), then write the ROM to the donor PCB.
• For drives where the donor PCB is electrically incompatible at the motor driver level, engineers transplant individual donor components (capacitors, motor driver chips, voltage regulators) onto the original PCB rather than swapping the whole PCB.

Pre-amp board

The pre-amplifier on the head stack assembly is a small chip that boosts the tiny signal from the heads before it reaches the drive’s main controller. Pre-amp failures are less common than head failures but produce similar symptoms. Pre-amp transplants require precise soldering work and a compatible donor’s pre-amp board.

Platter sets (rare and risky)

When the drive’s mechanism has failed but the platters and the data on them are intact, the platters can in principle be transplanted to a donor’s working chassis. This is one of the highest-difficulty recovery procedures; the platters must be reinstalled in exact alignment with their original positions, and even slight misalignment makes the data unreadable. Multi-platter swaps are particularly demanding because each platter’s relative orientation to the others must be preserved. Recovery engineers use specialized jigs to maintain platter alignment during transfer.

Motors (very rare)

Hard drive spindle motors fail occasionally, but motor swaps are uncommon because the motor is integrated into the chassis. In practice, motor failure typically motivates platter transplant to a healthy donor chassis rather than motor replacement in the original chassis.

External drive bridge boards

External hard drives like the WD My Passport and Elements series add another layer: hardware encryption at the USB-SATA bridge board level. Even when the internal drive is a standard WD Blue or WD Green, the bridge board encrypts data before it reaches the platters. Losing the bridge board means losing the encryption key. Recovery preserves and transplants the original bridge board electronics whenever possible; if the bridge board is destroyed, recovery may depend on whether the encryption implementation allows key extraction from the destroyed board.

Where donor drives come from is a logistical question that affects recovery cost, recovery timeline, and whether recovery is feasible at all for a given drive model.⁷

Specialized parts suppliers

Several suppliers specialize in selling donor drives and individual parts to recovery labs:

• Donor Drives LLC: US-based supplier with over 30,000 unique drive listings and 100,000 total drives in stock. Partnered with ACE Lab so that PC-3000 software can search Donor Drives’ inventory directly.
• HDD Donor: India-based supplier with detailed technical specifications for matching.
• HDD Zone: another commercial parts supplier serving the recovery industry.

These suppliers maintain detailed compatibility metadata (firmware revision, DCM, preamp version, ROM version) that recovery technicians use to verify matches before purchasing.

In-house lab inventories

Major recovery labs maintain their own inventories built up over years of operations. Datarecovery.com references a stock of tens of thousands of drives meticulously cataloged in proprietary databases. DriveSavers references 20,000 parts and drives stored in dedicated cleanroom-zone inventory areas. Having the donor on-hand eliminates the donor-sourcing wait time; in-house inventory is one of the competitive advantages large labs have over smaller recovery services.

Secondary marketplaces

eBay and similar platforms are common sources for older drive models that aren’t available through specialized suppliers. The risk is that listings often lack the detailed metadata recovery work needs; technicians may need to purchase and test multiple candidates before finding a true match.

Peer networks

Recovery technicians sometimes share parts informally, especially for very rare drives. Industry peer networks include forums, professional associations, and informal contact networks built up over years of operation.

Cost ranges

Donor drive costs vary significantly:

• Common consumer drives: $50 to $150 from specialized suppliers.
• Older or rare configurations: $200 to $400.
• Discontinued or hard-to-find models: $500 to over $1,000 individually.
• Enterprise SAS drives or rare server-class drives: can exceed $1,000 each.

When donors cannot be sourced

For very rare drives, the question is sometimes not how much the donor costs but whether one can be found at all. Recovery labs maintain wait lists for some drive models. For some discontinued enterprise drives, recovery is feasible only when a donor becomes available, with no specific timeline. Customers in this situation may face open-ended wait times or, in worst cases, recovery may be effectively impossible because no donor exists.

Why recovery quotes vary

The donor-sourcing reality explains why recovery quotes can vary substantially between cases that look superficially similar. A common 1TB consumer drive has plentiful donors at $50-$150 each. A discontinued 18TB enterprise SAS drive may have a single donor available worldwide at $1,500. Both might require the same labor (a head swap), but the donor cost difference flows through to the customer’s quote.