Data Recovery Glossary

Mechanical arm that moves the read/write heads across the platters. Driven by a voice coil motor.

Fine-tuning settings unique to each hard drive: head calibration, read/write channel equalisation, servo parameters. Calculated at the factory for each individual HDD. Using adaptives from another drive — even of the identical model — causes instability or data loss.

Apple File System — modern file system for Mac, iPhone and iPad since 2017. Optimized for SSD, with snapshots, native encryption and clones.

A physically damaged or unstable, unreadable sector. The drive manages these via internal tables (P-List, G-List). A growing number of bad sectors signals imminent degradation.

A particle-controlled environment (ISO 5 standard) where hard drive opening procedures are performed. A single dust particle can scratch the magnetic surface and destroy data. Belgium Data Recovery operates its cleanroom in Brussels.

The characteristic sound of a hard drive whose heads fail to read calibration data at startup. A near-certain sign of head failure or Service Area damage. Requires cleanroom intervention.

Conventional Magnetic Recording — standard magnetic recording without track overlap. Faster than SMR for random writes.

The software component of PC-3000 dedicated to data extraction: cloning, selective reading, file system reconstruction and deleted file recovery.

State of a RAID array where one or more drives are missing or failed. The system continues to operate but without redundancy.

A hard drive identical to the damaged one, used to harvest spare parts (heads, PCB, motor). Strict compatibility is essential: same model, same firmware, sometimes even the same country of manufacture.

Data protection through cryptographic algorithms (BitLocker, FileVault, LUKS). Recovery from an encrypted drive requires the decryption key — without it, data is mathematically inaccessible.

File Allocation Table — simple file systems used on USB drives and SD cards. Vulnerable to write interruptions.

A recovery technique that scans the drive sector by sector to identify files by their signature (header/footer), without using file system metadata. A last resort when the logical structure is lost.

Embedded microcode that controls the hard drive. Partially stored in the PCB ROM and partially on the platters (Service Area). Corrupted firmware renders the drive inoperable — data is intact but inaccessible without firmware repair.

A dynamic defect table that grows during the drive's lifetime. When the drive encounters an unstable sector in the user area, it reallocates it from a reserve pool and adds it to the G-List. A rapidly growing G-List signals drive degradation.

Magnetic storage device composed of spinning platters and read/write heads. Capacity is measured in gigabytes (GB) or terabytes (TB).

A device dedicated to sector-by-sector copying from an unstable drive to a healthy one. Manages critical parameters: read time-outs, skipping unreadable sectors, software-controlled disabling of problematic heads, mapping of damaged areas. Industry-standard tools: PC-3000 Data Extractor, DeepSpar DDI.

The sealed enclosure of a hard drive containing the platters, heads and preamplifier. Filled with filtered air (or helium in high-capacity drives). Must never be opened outside a cleanroom: dust contamination destroys data permanently.

Physical contact between the read/write head and the platter. Catastrophic damage: the magnetic surface is scratched, and data under the scratch is lost. Occurs from impact, dropping, or mechanical wear.

A table in the drive's ROM that maps logical heads to physical heads and their wiring to the preamplifier. An incorrect head map prevents the drive from starting up.

A mechanical device that catches the heads when the drive spins down, holding them safely off the platter surface. Prevents head-to-platter contact at rest (stiction). In 2.5" drives, parking often occurs directly on a dedicated zone of the platter instead.

A cleanroom procedure to replace damaged read/write heads with heads taken from a compatible donor drive. A delicate operation, reserved for equipped professionals.

A high-capacity hard drive (8 TB and above) whose interior is filled with helium instead of air. Helium reduces turbulence, allowing up to 9 platters to be stacked in a standard enclosure. Critical recovery constraint: if opened, helium escapes and the heads can no longer fly — the drive becomes inoperable within seconds.

Legacy Apple file system (Mac OS Extended), predecessor to APFS. Still present on many external drives.

A technique that involves replacing the drive's PCB (circuit board) while it is powered on. Used to bypass Service Area access blocks when the drive refuses to initialise normally.

Sector-by-sector copy from the damaged drive to a healthy one. An essential preliminary step before any logical recovery attempt. Performed with specialized hardware (PC-3000, DeepSpar) that handles unreadable sectors without blocking.

Logical Block Addressing — logical sector addressing. The operating system sees the drive as a linear sequence of numbered sectors.

A file containing a copy of essential firmware modules (overlays, tables). Loaded into the drive's RAM via the technological port to enable initialisation when the Service Area is damaged. A key step in many recovery procedures.

Recovery on a physically functional drive: deleted files, accidental formatting, file system corruption. Does not require opening the drive.

Compact physical form factor for SSDs, used in modern laptops. Can be SATA or NVMe depending on the connector.

Master Boot Record / GUID Partition Table — tables describing a disk's partition structure. Corruption of this table renders all partitions inaccessible.

Central database of the NTFS file system containing metadata for each file (name, size, location, dates). MFT corruption makes files invisible.

Type of non-volatile memory used in SSDs, USB drives and SD cards. Available in several densities: SLC (1 bit/cell), MLC (2 bits), TLC (3 bits), QLC (4 bits). Higher density means shorter lifespan.

Network Attached Storage — a network storage server. Common brands: Synology, QNAP. NAS failures are often related to the internal RAID controller or configuration errors.

The fundamental principle of professional recovery: the diagnosis is free, and the client only pays if data is successfully recovered. Zero-risk financial guarantee.

New Technology File System — the Windows file system. Uses a Master File Table (MFT) to index files.

Non-Volatile Memory Express — a communication protocol designed for SSDs, leveraging PCIe bus speed. Up to 7 times faster than SATA.

Factory defect table recorded during hard drive manufacturing. Contains physically defective sectors detected at the factory. This list is permanent and is never erased, even after a full format.

Calculated information derived from data, allowing reconstruction of a missing block. Used in RAID 5 and 6.

Logical division of a physical drive into separate volumes. The partition table (MBR or GPT) describes their location.

A professional HDD diagnostic and repair system developed by ACELab. Enables firmware access, translator repair, intelligent cloning and data extraction. The industry-standard tool in professional data recovery.

Electronic board mounted under the hard drive. Contains the controller, cache memory and voltage regulator. Often damaged by power surges or incorrect power supply.

Replacement of the hard drive's electronic board. Often requires transferring the original ROM (containing calibration parameters specific to the drive) to the new board.

Recovery requiring hardware intervention: head replacement, PCB replacement, or motor replacement. Involves cleanroom work and specialized equipment.

Aluminum or glass disk coated with a magnetic layer, where data is stored. A hard drive contains one or more platters.

An electronic chip located inside the sealed enclosure, on the actuator arm. Routes signals between the heads and the read/write channel, and amplifies read signals in the microvolt range. A failed preamp results in silent or erratic heads.

Data alternately split across N drives for performance. No redundancy: losing a single drive means losing all data.

Data duplicated identically on 2 drives. If one drive fails, the other contains all data.

Mirroring of two striped sets. Combines performance and redundancy. Tolerates one failure per mirror. Minimum 4 drives.

Striping with distributed parity across a minimum of 3 drives. Tolerates a single drive failure. Rebuilding after drive replacement is a high-risk phase.

Like RAID 5 but with double parity — tolerates 2 simultaneous drive failures. Requires a minimum of 4 drives.

Low-level drive analysis to find data without relying on file system structure. Useful when the partition table or file system is completely corrupted.

Miniature component that reads and writes data on the platter, flying at a distance thinner than a human hair. The head never touches the platter in normal operation. A shock can cause a Head Crash: destructive head-to-platter contact.

Process of recalculating and rewriting data onto a replacement drive after a failure. An intensely demanding phase for the remaining drives.

Memory cards used in cameras, camcorders and recorders. Recovery is often possible as long as the card has not been overwritten after data loss.

Smallest addressable unit on a disk, typically 512 bytes or 4096 bytes (Advanced Format).

Reserved area on the platters containing firmware, defect tables, translator and calibration parameters. Inaccessible to the user. SA damage is a serious failure.

Self-Monitoring, Analysis and Reporting Technology — a built-in drive monitoring system that detects and reports early warning signs of failure (reallocated sectors, read errors, excessive temperature).

Shingled Magnetic Recording — a hard drive recording technology where tracks overlap like roof tiles. Allows higher data density but slows rewrites. Complicates certain recovery procedures.

Motor that spins the platters at constant speed (typically 5400 or 7200 RPM). A seized spindle motor is a common failure.

Storage device with no moving parts, using NAND flash memory. Faster and more shock-resistant than an HDD, but with a limited write lifespan.

Mapping table between logical addresses (LBA) and physical addresses (cylinder, head, sector). If the translator is damaged, the drive can no longer locate data.

An offset between logical addressing and physical data, occurring when a head fails or the translator table becomes corrupted. The data is still present but at a shifted position. Corrected by searching for synchronisation points (FAT, MFT) in Data Extractor.

A command allowing the operating system to inform the SSD which data blocks are no longer in use. The SSD can then erase them in the background. On SSDs, after file deletion, freed blocks can be erased almost instantly — hence the importance of powering off the device immediately after accidental deletion.

On SSDs with active TRIM, file deletion triggers immediate block erasure by the SSD controller. Unlike traditional HDDs, deleted data can disappear within seconds. The absolute rule: power off the device immediately.

Removable storage using NAND flash memory. The most common failure is a broken solder joint on the connector or a failed controller.