How Donor Drives Are Matched for Head Swaps

A head swap requires transplanting the entire Head Stack Assembly (HSA) from a compatible donor drive into the patient drive (the drive with failed heads). The donor heads must be mechanically compatible with the patient's platters and electronically compatible with the patient's firmware and preamp circuitry. Matching by model number alone is not sufficient. Hard drive manufacturers produce the same model number across multiple hardware revisions, with different head components, preamp chips, and firmware variations within a single model line. Donor matching is a prerequisite for head-swap cases in our hard drive data recovery workflow.

What Is Matched Between the Donor and the Patient Drive?

1. Preamp gain matching

The preamp on the HSA flex cable amplifies head signals at a calibrated gain stage. When donor and patient preamp revisions differ, the read-back signal arrives at the controller channel at the wrong amplitude.

2. Channel coefficients (FIR equalizer and gain)

The read channel uses a Finite Impulse Response (FIR) equalizer to flatten the partial-response waveform recovered from the preamp, followed by a Viterbi detector that resolves the equalized signal into NRZ bit decisions. The equalizer tap coefficients and their associated gain and target settings are head-specific adaptive values stored in the System Area. The detector downstream reads whatever the equalizer hands it; it holds no per-head calibration of its own. The patient's coefficients were trained against the patient's heads; loading them against donor heads produces equalization residuals that the Viterbi detector mis-decodes as bit errors. PC-3000 reads the donor's channel coefficients from the donor SA before the swap and writes them into the patient firmware as part of adaptive transfer, so the equalizer is targeted at the heads that will actually be installed.

3. Microjog offsets

Per-head radial position deltas stored in adaptive tables. Detailed mechanics are documented in the SA Adaptives and Microjog Calibration section below.

4. HSA family and firmware revision compatibility

A donor labeled with the same model number routinely fails because the HSA family or firmware sub-revision differs. WD Marvell drives split on the DCM J or 2 anchor character and the character preceding it, which encode the head stack supplier and preamp. Firmware revision is matched as a precondition, but firmware-revision match alone is not sufficient when the HSA family within the revision has changed. This is why same-model donors fail more often than the model number alone suggests.

5. HGA generation on multi-platter helium drives

Helium-sealed multi-platter families (WD Ultrastar DC HC series, Seagate Exos X) iterate Head Gimbal Assembly generations more frequently than air-filled families because each revision ships as a separate SKU rather than as a running change to a single SKU. The donor window tightens from months to weeks. Helium head swap pricing uses $3,000–$4,500 per the helium HDD pricing tiers.

How Does the Donor Selection Decision Cascade Work?

1. Phase A. Patient Label Analytics. Transcribe the metadata that determines candidate filtering. For Western Digital units, record the MDL string (16-digit or 17-digit format) and the Drive Configuration Matrix (DCM), which encodes head stack vendor and preamp tuning in specific character positions. For Seagate units, record Model Number, Part Number prefix, Site Code (WU, SU, TK), and Date Code. Seagate Date Codes use a proprietary fiscal-year format and must be converted to a standard calendar date before the 12-week donor window can be evaluated.
2. Phase B. Candidate Donor Lookup. Candidate donors are filtered against the patient identifying fields recorded in Phase A before they are physically acquired.
3. Phase C. External Label Cross-Check. When a candidate donor arrives, the WD model string is re-verified against the patient. DCM alignment uses the J or 2 anchor character near the end of the DCM string. The anchor and the single character immediately preceding it encode the HSA supplier and preamp tuning, and must match exactly between patient and donor.
4. Phase D. ROM Dump and Shadow Module Verification. Before the donor seal is broken, PC-3000 reads the donor ROM through vendor-specific commands. The Service Area shadow copies are read in a separate step: WD Marvell drives are forced into Kernel Mode and an LDR loader is uploaded to controller RAM, which permits reading Module 102 and Module 103, the platter-resident shadows of the ROM head map and the SA adaptives. Seagate F3 drives are accessed via the serial diagnostic COM port at 38,400 baud. The SPI flash ROM is first extracted in Boot Code mode. PC-3000 then generates a Tech Mode unlock patch from that image, which is loaded into RAM to bypass the Diagnostic Port Lock for subsequent terminal access.
5. Phase E. Internal Preamp and Adaptive Verification. If the ROM dump confirms compatibility, the donor is staged for internal inspection.

What Disqualifies a Donor Before the Clean Bench?

Donor drives cost from hundreds to thousands of dollars, and a misjudged candidate destroys both the donor heads and the patient platters on first spin-up. The following conditions remove a donor from consideration before any HSA extraction begins. Each is observable from the label, the ROM dump, or a microscopic platter inspection performed with the patient cover off but the donor still sealed.

Mismatched physical head count or geometry

A donor may have more heads than the patient as long as the active heads sit in the same spatial positions across the platter stack. A donor with fewer heads, or with an active head map that does not align geometrically with the patient chassis, is rejected.

Visible platter damage and crash-rings

Before HSA extraction, the patient platters are inspected under the 0.02 micron ULPA clean bench. A concentric crash-ring scored through the CoCrPt magnetic coating means the failed head has lifted particulate matter into the HDA. Installing a pristine donor HSA into a contaminated HDA destroys the donor heads on the first spindle rotation. Recovery on a crash-ring patient requires platter burnishing and media cleaning under the bench before the donor HSA is committed.

Date of Manufacture beyond the 12-week window

The industry baseline is a 12-week DOM window between patient and donor. Match rate degrades as the window widens because manufacturers alter internal components across production runs within a single model line.

DCM anchor character deviation (WD)

The Western Digital DCM is not arbitrary. The J or 2 anchor character near the end of the DCM string, and the single character immediately preceding it, encode the HSA vendor and preamp tuning configuration. A donor whose anchor pair does not match the patient anchor pair is disqualified, even when the model number, firmware revision, and Date of Manufacture all match.

How Is the Head Map Verified on the PC-3000?

The logical head map tells the controller which physical read/write elements to route I/O through. Verifying the donor head map against the patient head map before committing the swap, and selectively disabling weak heads on the donor after the swap, are both performed through the PC-3000 utility against specific firmware modules. Procedural context for the swap itself is documented in what a head swap involves.

Verification sequence

1. Force the drive into Kernel mode under PC-3000 control so the Service Area is reachable while the controller is bypassing normal boot.
2. Navigate Tools, Utility extensions, Modules directory to inspect Service Area integrity.
3. Read Module 0A as the head map of physical head positions active in the patient configuration.
4. Compare the patient head map against the donor ROM head map extracted in Phase D. The donor must support the patient configuration exactly, or a superset of it.

Selective head disablement after the swap

If a transplanted donor HSA presents one marginal head, PC-3000 can logically retire that element from the active translation pool. On Seagate F3 the path is Zones and Heads Inactivation through the P-List menu. Disabling a single head on a 4-head 2 TB Rosewood drive removes access to one platter surface, roughly 500 GB of the 2 TB volume. The remaining stable heads are imaged first under DeepSpar Disk Imager with conservative timeouts, and the disabled head is re-engaged in a later pass with aggressive timeout parameters to recover the surface it controls.

Why Does Firmware Revision Matching Matter?

The drive's firmware revision is the primary matching criterion. The firmware controls how the drive communicates with the heads: signal timing, read channel calibration, servo decoding parameters, and write current profiles. Heads from a donor with a different firmware revision may not work because the patient drive's firmware expects specific electrical characteristics from the heads that the donor heads do not provide.

Firmware revisions are printed on the drive label. For Seagate drives, this is a four-character code (e.g., CC26, SDM1, 0001). For Western Digital, the firmware revision is part of the extended model number. The firmware revision indicates the generation of controller code and, by extension, the generation of head technology the firmware is calibrated for.

Within a firmware revision, there can be sub-revisions that affect compatibility. Two Grenada drives with firmware "CC26" manufactured six months apart may have different micro-code patches. In most cases, same firmware revision is sufficient. In some Seagate Rosewood drives, even drives with the same firmware revision but from different manufacturing sites (identifiable by the Site Code on the label) have different head compatibility.

How Does the Head Map Affect Donor Compatibility?

A drive's head map specifies which heads are installed and active. A two-platter drive can have 2, 3, or 4 heads depending on the capacity variant. A Seagate Rosewood ST2000LM007 (2 TB) uses 4 heads across 2 platters. The ST500LM030 (500 GB) uses 2 heads on 1 platter. Both are "Rosewood" drives, but their head assemblies are physically different.

The head map is stored in the drive's firmware and defines which physical head positions are active and how the firmware addresses them. A 3-head donor HSA cannot be used in a 4-head patient drive, because the donor carries no head for the fourth surface.

Why Must the Preamp Chip Match?

The preamp is a small IC mounted on the HSA flex cable, inside the sealed drive cavity. It amplifies the microvolt signals from the read heads and drives the write current to the write heads. The preamp model must match between donor and patient because the controller's read channel is calibrated for the specific signal characteristics of that preamp.

Preamp models can be identified by the marking on the chip, visible when the drive is opened. Common preamp manufacturers include Texas Instruments, STMicroelectronics, Broadcom (Avago), and Renesas.

What Happens to Adaptive Parameters After a Head Swap?

Every hard drive generates a unique set of adaptive parameters during factory self-scan. These parameters record the specific calibration data for the drive's individual heads: optimal read channel settings, write current values, fly height compensation, and servo tracking offsets.

After a head swap, the patient drive's adaptive parameters no longer match the installed heads. The parameters were calibrated for the original heads, not the donor heads. In some cases, the drive can still read with minor degradation. In other cases, the mismatch prevents the drive from reading its own System Area, causing it to fail initialization.

PC-3000 can modify adaptive parameters after a head swap. The technician can load the donor drive's adaptive parameters into the patient drive's firmware, aligning the calibration with the installed heads. This is not always necessary (some drive families tolerate mismatched adaptives well enough for imaging), but it improves read stability and reduces errors on drives where the mismatch causes issues.

Why Do Manufacturing Date and Factory Site Affect Donor Matching?

The closer the donor is to the patient in manufacturing date and production site, the higher the compatibility probability. Drives manufactured in the same batch at the same factory use the same component lots: same head wafer, same preamp batch, same platter lot. Component-level consistency within a production batch is high.

Western Digital encodes manufacturing information in the DCM (Drive Configuration Matrix) printed on the label. Two drives with the same model number and firmware revision but different DCM codes may have incompatible heads.

Seagate uses a combination of the Part Number (PN), Site Code, and Date of Manufacture printed on the label. The Site Code identifies the factory (e.g., WU for Wuxi, SU for Suzhou, TK for Thailand). Two Seagate drives with matching model numbers and firmware revisions but different Site Codes or Part Numbers may have incompatible head assemblies.

How Labs Maintain Donor Inventory

Professional recovery labs maintain an inventory of donor drives organized by manufacturer, model family, firmware revision, head map, and manufacturing date range. Common drive families that fail frequently (Seagate Rosewood, WD Blue/Green 2.5", Samsung Spinpoint M8) are stocked in higher quantities.

When a patient drive arrives, the technician identifies the required donor specifications from the drive label and firmware. If the lab has a matching donor in stock, the head swap can proceed immediately. If not, the lab sources one from supplier networks, which may take 1-5 days depending on the drive's rarity.

Donor inventory depth is one reason the size of a lab's parts library matters when comparing data recovery labs; a lab that already stocks your drive family can begin the head swap without waiting on a supplier order.

Donor drives are purchased specifically as parts inventory. They are functional drives that have been verified to read and write normally. Using a donor from a failed drive (e.g., a drive that had bad sectors but working heads) is possible but risky: the heads may be degraded even if they currently function.

How Do Firmware Families Differ by Manufacturer?

Hard drive manufacturers iterate on base firmware architectures across multiple product generations. Recognizing which firmware family a drive belongs to is the first step in donor matching, because cross-family donors are incompatible even when the model number prefix looks similar. Each family uses a distinct read channel configuration, SA module layout, & head addressing scheme.

Seagate F3 Architecture: Grenada and Rosewood

Seagate's F3 architecture covers drives where the firmware revision is a short alphanumeric code without a period (e.g., CC49, SBK2, SDM1). Within F3, these sub-families have distinct matching requirements:

Grenada (7200.14 desktop)

Desktop 3.5" drives including the Barracuda ST1000DM003 & ST2000DM001. Grenada matching depends on firmware revision, head map, & preamp chip. The preamp revision is visible on the HSA flex cable when the drive is opened.

Rosewood (2.5" mobile)

The Rosewood family includes the ST1000LM035, ST2000LM007, & ST500LM030. These are among the most common drives in recovery labs. Rosewood matching is complicated because the preamp revision is not printed on the drive label, and the serial terminal is locked on most units. The preamp must be identified by opening the drive or estimated from the Date of Manufacture.

Western Digital Marvell-Based Architecture

Western Digital transitioned from older Caviar IDE/SATA controllers to Marvell-based MCU architectures. Modern WD drives are categorized into Marvell Version 1 & Version 2, distinguished by the family code in the model number.

WD donor matching requires aligning the full model number, the physical head map, & specific characters within the DCM (Drive Configuration Matrix). The J or 2 anchor character near the end of the DCM, with the character immediately preceding it, encodes the head stack supplier & preamp. Two drives with identical model numbers & firmware but different DCM anchor characters have physically different head assemblies from different component vendors.

WD firmware stores the head map in ROM Module 0A. Module 47 holds the SA Adaptives (servo parameters & head-specific calibration).

Toshiba MQ & MK Series

For the older MK series (MK6475GSX), matching the full model number & PCB family number is typically sufficient. For the modern MQ series (MQ01ABD, MQ04ABF), matching the full model number & the HDD Code printed on the label covers most compatibility cases.

SA Adaptives & Microjog Calibration

Service Area (SA) adaptive parameters are head-specific calibration values generated during factory testing. After a head swap, these parameters no longer match the installed donor heads. PC-3000 can transfer the donor's adaptives into the patient drive's firmware to restore read stability, but the process varies by manufacturer & firmware family.

On Western Digital Marvell-based drives, SA Adaptives are stored in Module 47. This module contains voltage settings, read channel gain profiles, & servo calibration values specific to each head position. If the donor heads deviate from the patient's Module 47 values, the drive may fail to read its own Service Area on power-up, resulting in a clicking loop or immediate head park. The technician uses PC-3000 to replace the patient's Module 47 with the donor's version, allowing the firmware to calibrate for the installed heads.

Microjog values are a subset of the adaptive data. During factory calibration, the drive measures microscopic alignment offsets for each head on the actuator arm & records compensation values. These values correct for physical variation in head placement that is unavoidable during HSA manufacturing. When a donor HSA has microjog values close to the patient's original values, the swap is more likely to produce stable reads without additional intervention. Large deviations in microjog values indicate the donor heads are physically misaligned relative to what the patient firmware expects, which causes read errors & sector instability during imaging.

Why Does the Patient's ROM Transfer to the Donor PCB, Not the Reverse?

A common question from customers is whether a head swap is accompanied by a ROM swap in the same direction. It is not. The ROM contents follow the patient's heads and platters; never the donor's. This is because the ROM holds adaptive data that was burned during factory calibration against the original HDA, and the firmware expects that data to match the physical media it is reading. Transplanting a donor ROM wholesale onto a patient HDA produces controller errors that look identical to head failure but are actually firmware misconfiguration.

On Seagate F3 drives, the ROM chip holds the bootstrap code and the baseline adaptive parameters (RAP, CAP, SAP) that let the controller locate and track the Service Area; the primary translator (SysFile 28) lives in the Service Area on the platters, not in the ROM. The patient's heads were calibrated against the patient's platters, so the patient ROM must move onto the donor PCB (or equivalently, the donor ROM is replaced with the patient's ROM contents via a programmer). A wholesale donor ROM swap commonly produces the LED 000000CC code on the F3 diagnostic port, or a Diag Err state where the controller cannot locate its own SA.

On Western Digital Marvell-based drives, Module 0A holds the head map and Module 47 holds the SA adaptives. Both pin adaptive data to the physical controller and its factory-calibrated HDA. Using a donor ROM wholesale causes the controller to apply donor servo parameters to the patient HDA, which produces a hardware retry loop (repeated read-channel calibration attempts that never converge) or a slow-responding error where the drive takes several seconds to answer IDENTIFY DEVICE and then fails to initialize the user area.

The practical workflow at our Austin data recovery lab is to read the patient ROM with a programmer clip before the HSA swap is attempted, store the dump, and write the patient ROM contents onto the donor PCB. If the donor PCB is incompatible at the motor-driver level, the donor's electrical components are populated onto the patient's PCB instead, preserving the patient's ROM in its original socket.

How Are Date-Code Window and Site-Code Used for Donor Matching?

Date of Manufacture is one of the most load-bearing external matching criteria. Industry practice is to match donors within approximately 3 months (12 weeks) of the patient's Date of Manufacture. Some labs stretch this window to 6 months when rare drive families leave no tighter option. Match rate degrades as the window widens because manufacturers iterate head wafer design, change preamp vendors, or alter platter carbon overcoat thickness between production batches. A donor from outside the window often looks electrically similar on paper and still produces unstable reads in the patient drive.

The full fingerprint is a combination of three fields. The Site Code (WU for Wuxi, SU for Suzhou, TK for Thailand) identifies the factory and, by extension, the component vendors the factory was sourcing during that production window. The Date of Manufacture anchors the batch within the manufacturer's component-change timeline. Together, Part Number prefix + Site Code + DOM act as an HSA lot fingerprint.

Helium drive donor windows are tighter. Helium-sealed families (WD Ultrastar DC HC series, Seagate Exos X) iterate internal components more frequently within a single model line because the sealed-cavity design makes post-production component revisions cheaper to ship as a separate SKU rather than as a running change. A helium donor window measured in weeks rather than months is standard practice.

What Is Verified at the Clean Bench Before a Head Swap?

Before the patient drive is opened, the vertical laminar flow bench is validated and the donor HSA is staged. The 0.02 micron ULPA-filtered bench provides a particle-controlled localized environment at the open drive. The lab uses a particle counter to verify the bench before opening the drive.

Visual platter inspection runs under high-magnification illumination and checks for three primary defects. Rotational scoring appears as concentric rings around the platter, indicating a head has touched the surface during prior operation. Crash rings are darker zones where the head has scraped the CoCrPt magnetic coating off the substrate; crash rings mean the donor HSA will be sacrificed if installed. Embedded debris is any foreign particle adhered to the platter surface; a single particle requires cleaning with a platter-safe procedure before the donor HSA is brought into contact with the disk.

Slider count verification compares the physical head count on the patient HSA to the logical head map reported by firmware. A 6-head drive must show 6 intact sliders on the HSA arm comb. A missing or damaged slider indicates the head map and the physical assembly are out of sync, and the donor selection must be revisited against the actual physical configuration rather than the label-reported head count.

HSA Extraction and Transplant Procedure

The physical transfer of a Head Stack Assembly from donor to patient is a bench procedure, not a single motion. Every step is performed inside the 0.02 micron ULPA vertical laminar flow bench with the drive cavity open. The tooling is model-family-specific, and the risk at each step is contact between slider and platter surface. Once a slider lands on a spinning or stopped platter with any lateral force, the CoCrPt magnetic coating is scored and the platter track is lost for that revolution; repeated contact creates the crash ring pattern described in the clean-bench verification section above.

1. Head comb staging. A head comb is a set of thin polymer or shim-steel fingers sized to the exact inter-platter gap of the target drive family. The comb slides between the platters and separates the read/write heads before the HSA is lifted off the pivot. Comb dimensions are specific to drive family: a 3.5" enterprise comb will not fit a 2.5" Rosewood, and a Rosewood comb will bind in an Ultrastar helium cavity. The correct comb is selected by drive family before the patient cover is removed and kept under the laminar flow until installation.
2. Actuator pivot release. The HSA is held to the baseplate by a pivot screw or magnetic latch (depending on family). The head stack is parked on the ramp load/unload structure or on the inner crash stop, and the comb is inserted between the platters to capture the sliders. Only after the comb is seated can the pivot be released.
3. Platter rotation lock. On drives with free-spinning spindles (some 3.5" desktop families), a spindle lock pin is inserted through the motor hub to prevent platter rotation during HSA removal. Any rotation while the comb is between the platters drags the sliders against the comb surface and abrades the air-bearing face. On sealed helium drives, the cover reseal procedure after a head swap requires helium refill from a calibrated line per our helium-HDD recovery workflow.
4. Donor HSA preparation. The donor drive is opened in parallel under the same bench. The donor HSA is combed and lifted identically. The donor ROM is not transferred; only the physical head stack is moved. The patient ROM contents have already been programmed onto the donor PCB (or the donor PCB has been swapped onto the patient body) before this step, per the ROM binding procedure in the section above.
5. Transplant and comb withdrawal. The donor HSA is seated onto the patient pivot with the comb still holding the sliders apart. The pivot screw or latch is reattached. The comb is withdrawn in a single smooth motion parallel to the platter surface; a tilted withdrawal brings a slider into momentary contact with the platter and can score the landing zone. The cover is replaced before power is applied to prevent airflow contamination of the newly transplanted heads.
6. First power cycle under PC-3000 control. The drive is connected to the PC-3000 Portable III or Express terminal, not to a normal SATA port. First power is issued with the terminal recording the boot sequence so that any SA read failure, adaptive mismatch, or preamp error is captured in the log before the firmware commits a write. If the drive fails to spin up, the procedure aborts and the donor selection is revisited before a second attempt is staged.

Extraction procedure varies across families. WD 2.5" Marvell drives (WD10SPZX, WD20SPZX) use a magnetic latch instead of a screw on some sub-revisions, which the technician identifies visually before lifting. Helium drives (Ultrastar DC HC series, Exos X) require the additional step of breaking the cover hermetic seal under the bench and refilling the cavity with helium from a calibrated line before the cover is re-bonded. Helium head swaps use $3,000–$4,500; surface damage cases use $4,000–$5,000, plus helium and donor costs.

PC-3000 Head Testing Workflow

After installing a donor HSA, the technician uses PC-3000 to evaluate whether the donor heads can read the patient drive's data. This is a structured diagnostic sequence, not a single pass/fail test. The workflow determines head compatibility, identifies weak heads, & guides the imaging strategy.

1. SA Module Read Test. Power on the patient drive with the donor HSA installed. PC-3000 attempts to read the Service Area modules (the firmware stored on reserved platter tracks). If the drive reads its SA successfully, the donor heads are electrically compatible with the patient's controller & preamp circuit. If the SA read fails, the heads are incompatible or the adaptives need transfer.
2. Head Stability Evaluation. PC-3000 reads sample sectors from each head position & reports the error rate per head. Donor heads are never perfectly calibrated for the patient's platters; some read degradation is expected. The technician evaluates whether each head reads well enough for sustained imaging or if specific heads need to be disabled in the head map to prevent platter damage from a weak head dragging.
3. Conditional Adaptive Transfer. If the SA read succeeded but the error rate is high, the technician transfers the donor's adaptive parameters into the patient firmware. On WD drives, this means replacing Module 47. On Seagate F3 drives, this means editing the SA adaptive tables. The drive is then power-cycled & the head stability test is repeated.
4. Selective Head Map Configuration. If one or more heads are unstable after adaptive transfer, PC-3000 can disable specific heads in the firmware head map. The imaging proceeds using only the stable heads, recovering data from the platter surfaces those heads can reach. Data on surfaces served by the disabled heads may require a second donor attempt with a better-matched HSA.

How Does Donor Matching Work on Modern 20TB+ Enterprise Drives?

Enterprise HDDs released from 2024 onward introduce recording-layer technologies that tighten donor matching beyond the rules that apply to PMR and helium-PMR families. The three platforms below dominate current high-capacity recovery casework, and each one changes which fields on the patient label become hard match criteria. Donor windows shrink, cross-family substitution is ruled out, and additional verification steps run on the PC-3000 Portable III before any head-comb work begins. The procedures referenced here run inside our in-house mechanical recovery lab under the same 0.02 micron ULPA clean bench used for consumer drive head swaps.

WD Ultrastar DC HC560 and HC580 TSA HelioSeal

The Ultrastar DC HC560 (20 TB) and HC580 (24 TB CMR) families add a Triple-Stage Actuator (TSA) on top of the primary VCM and the secondary milli-actuator.

The practical effect on donor selection is a donor window measured in weeks rather than the standard 3-month window used for older PMR helium drives. The full DCM string on the label becomes a hard match criterion.

Seagate Exos X22 and X24 TDMR Dual-Reader

The Exos X22 (22 TB) and X24 (24 TB) families use Two-Dimensional Magnetic Recording (TDMR) heads.

Toshiba MG10 and MG11 FC-MAMR

The Toshiba MG10 (20 TB) and MG11 (24 TB) families use Flux Control Microwave-Assisted Magnetic Recording (FC-MAMR). Each write head carries a spin-torque oscillator that emits a microwave field at the gap, lowering the effective switching field of the recording layer so smaller bit cells can be written reliably. Donor matching uses the HDD Code printed on the drive label.

Modern HDD Family Quick Reference

Why Do OptiNAND Drives Require iNAND Migration During a Head Swap?

Western Digital OptiNAND drives move metadata that older designs kept inside the platter Service Area onto an iNAND UFS chip soldered to the PCB. The metadata includes the Repeatable Run-Out (RRO) tables, the Adjacent Track Interference (ATI) refresh accounting, and the ArmorCache emergency-power-off cache. A standard SPI ROM transplant procedure is not sufficient on these drives, because the head positioning servo loop depends on data that no longer lives on the platters. Donor PCB swaps and ROM transfers on OptiNAND drives require treating the iNAND as a separately migrated component.

The correct PCB transplant on an OptiNAND drive moves the iNAND UFS chip onto the donor PCB so the donor controller reads patient-specific RRO and ATI metadata, or moves the SoC and the iNAND together as a paired unit. The iNAND footprint on the PCB is a discrete UFS package next to the controller, and it is reworked under the same Atten 862 hot air station used for SPI ROM transplants, with FLIR thermal monitoring to keep the package within the manufacturer reflow profile. After the migration, the controller reads RRO and ATI from the patient iNAND and the original head positioning model is restored.

An iNAND failure that is independent of the heads is a distinct failure mode from a classic head crash. The patient HSA can be mechanically healthy, but with the iNAND unreadable the ATI and RRO indices are lost and the heads cannot stabilize tracking against recorded data.

What Are the Donor Matching Constraints for Mozaic HAMR Drives?

The Seagate Mozaic HAMR HSA carries an integrated nanophotonic laser and a plasmonic writer, which together perform the thermal writing that the superlattice platinum-alloy media requires.

Donor heads from any PMR or helium-PMR family are strictly incompatible with a Mozaic HAMR chassis. PMR heads carry no laser and no plasmonic writer, and the recording layer on PMR platters does not require heat-assisted writing. A PMR HSA installed on a HAMR chassis cannot write the recording layer at all.

Can a Larger-Capacity Donor Be Used for a Down-Binned Drive?

Manufacturers ship multi-platter HDAs with one or more heads disabled in firmware so a single mechanical platform can fill multiple lower-capacity SKUs. A 4-head HDA may ship as a 3-head or 2-head SKU with the surplus heads marked inactive in the head map. The HDA, the preamp, and the HSA generation are physically identical across the binned SKUs. This opens a procedural option in donor matching: a larger-capacity donor in the same family can be used for a down-binned patient when the active-head positions on the patient align with the physical-head positions on the donor.

On WD Marvell platforms, the active-head map is stored in Module 0A. The map is edited on the PC-3000 so the patient's active positions match the physical heads being installed from the donor HSA, and the surplus donor heads are masked inactive before the first power-up.

On Seagate F3 platforms, the Zones and Heads Inactivation P-List path is used to mark unused heads inactive on the donor side before the swap, or to retire a marginal head after the swap when a single donor head proves unstable on the patient's platter surface. The Heads Inactivation entries persist in the SA and survive subsequent power cycles, so the controller stops attempting to read tracks on the masked heads during imaging.

The standard disqualifiers still apply. A larger-capacity donor from a different HSA generation cannot be used regardless of capacity, because the preamp, head attachment geometry, and adaptive parameter set differ. A larger-capacity donor from a different preamp revision cannot be used either, even when the HSA generation matches, for the reasons documented in the preamp compatibility section. Down-bin substitution is a procedural option that expands the donor pool, not a way around the PC-3000 matching criteria.

What Are the Common Drive Family Matching Pitfalls?

Each drive family has specific compatibility traps that general matching rules do not cover. These pitfalls come from undocumented component changes, manufacturing site differences, & firmware sub-revisions that are not reflected on the drive label. The following notes apply to the drive families most commonly seen in recovery labs.

Seagate Rosewood Pitfalls

The Rosewood 2.5" family (ST1000LM035, ST2000LM007) accounts for a large share of consumer head-swap cases. The primary matching hazard is the preamp revision. At least two distinct preamp generations are in circulation, and neither the preamp part nor its revision is printed on the label. The Date of Manufacture printed on the label provides the best external estimate.

Verification is by opening the drive & reading the preamp marking on the HSA flex cable, or by reading the preamp identifier through PC-3000 after a successful SA initialization.

WD Blue & Green Marvell Platform

Modern WD 2.5" drives (WD10SPZX, WD20SPZX, WD10SPCX) use the Marvell controller platform. The DCM is the critical external matching reference. The J or 2 anchor character near the end of the string, with the character immediately preceding it, identifies the head stack supplier; donors that differ on those characters will have a physically different HSA even when the model number & firmware match.

Toshiba MQ Series

On Toshiba MQ drives (MQ01ABD050, MQ01ABD100, MQ04ABF100), matching the full model number is sufficient in most cases. The HDD Code printed on the label serves as a secondary criterion if the first donor produces unstable reads.

Samsung / Seagate Momentus Hybrid Drives

After Seagate acquired Samsung's HDD division, several drive models carry Seagate branding but use Samsung-designed internals. The ST1000LM024 is a Samsung Spinpoint M8 with a Seagate label. Donor matching for these drives must follow Samsung logic (full model number & PCB part number), not Seagate F3 logic. Using a Seagate F3 donor for a Seagate-branded Samsung drive will fail because the SA module layout, head addressing, & preamp circuitry are Samsung architecture. PC-3000's Samsung utility (not the Seagate F3 utility) is required for SA access & adaptive parameter management on these drives.

Head swap on Samsung/Seagate hybrid drives follows standard head swap pricing at $1,200–$1,500. Donor drives are matching drives used for parts. Typical donor cost: $50–$150 for common drives, $200–$400 for rare or high-capacity models. We source the cheapest compatible donor available. +$100 rush fee to move to the front of the queue

For complex donor-sourcing cases, customers can track progress through our in-house mechanical recovery lab, where the donor, adaptive transfer, and imaging steps are all performed under a single PC-3000 workstation without subcontracting.

Frequently Asked Questions