Hard Drive Data Recovery Glossary

Dave updated on Sep 22, 2022 to Knowledge Center

All its data is stored securely in a computer system's hard disk (HDD). In this glossary, you will find simple explanations about important terms that are required to understand the function of a hard disk and also helps you recognize and understand the purpose of the parts in a hard disk.



The process of retrieving data and storing it in a device. It also helps in recovering deleted information from your device.

Access Time

The total time passed between accessing the request to retrieve a particular piece of data and receiving that first bit of data.

Active Partition

It is a part of a hard drive that contains an operating system like Windows. Only one part of a hard drive can be set as an active partition.

Active Termination

It is a voltage controller that creates termination voltage. The voltage controller affirms that the data signal remains stable and robust.


The actuator is one of the essential parts of a hard drive, which governs the speed of a drive. A hard drive reads and writes its data through platters. Therefore, there are more than one actuator assemblies in a hard drive that helps it to access information more coherently and methodically.

The actuators move their heads in a specific direction, allowing the drive to read and write the data. The position of the actuator heads is so accurate that it will be able to find data anywhere on the disk.

Actuator Arm

The actuator contains read or write heads. These heads are controlled by an arm that moves, which puts the heads in their accurate position. It is coated with a thin magnetic material which allows its smooth functioning.

Adaptive Caching

It can magnify performance by adjusting and adapting to the program on the move. It is a cache engine found on a hard disk with ductile lifetime power.


There are different types of addresses in the hard drive industry. The address is related to a drive, and a variety of addresses are present: the unit address, cylinder address, or sector address.


Annualized Failure Rate is the process that determines the likelihood of a device deteriorating within its first year of functioning. A.F.R. is also a great fortune teller of how much one can rely on a hard drive. It also foregrounds the importance of redundancy in disk technology.


Allocation means preparing the hard drive for storing data. During the allocation process, criteria like size, label, and file system for data structure can be composed to the hard drive partition. So, allocation is a method to designate a particular hard drive area for a given file.


The act of deciding which command, device, or communication protocol commands or controls the operating environment. It is also a list of steps to assign machine resources, such as memory devices, to more than one program.

Areal Density

It is measured in square inches and determines the amount of data in bits recorded onto the surface of a disk. Its size density is calculated by multiplying the bit density by the track density.


To seek information about a local hard disk or network is when the A.S.P. drive object comes to play. The A.S.P. drive object plays the role of returning volume, free space, serial number drive type, etc.

To work with the resources of Drive Object, one has to create an occurrence of the Drive Object through the FileSystemObject object. The Drive Object's properties include available space, Drive Letter, Drive Type, FileSystem, FreeSpace, IsReady, Path, Root Folder, ShareName, etc.

Asynchronous Transmission

With the application of requests, individual bytes of information are synchronized. Advantages of asynchronous transmission include self-oriented characteristics, transmitter, receivers not needing synchronization, etc. The disadvantages include overheating start and stop bit, complications in handling errors, low transmission rate, etc.

AT Bus Attachment (ATA-4)

A physical confluence connects storage devices within a computer. It internally connects hard disks to the motherboard and executes basic input and output functions. The concept of A.T.A. is to connect moveable storage devices without an external controller. A.T.A. is a set of slender wires connected with a cable bus that transmits data in and out of the disk drives.  

Average Access Time

It is the minimum length of time taken to perform seeks. It is usually measured and calculated with 1/3 stroke.

Average Seek Time

It is the time the hard drive takes to move the read or write heads to a secure non-data landing zone and seal them in a particular location.



Refers to the quantity of data sent within a circuit space. It is also the speed at which data can be screened within guarded, integrated or hybrid graphics calculated in gigabytes per second. Disk bandwidth is the total number of bytes relocated, divided by the time between the first request for service and the completion of the last data transfer.

BIOS (Basic input/output system)

It is a program that guides a computer's essential and basic functions. BIOS connects the computer hardware to the operating system as soon as a computer is turned on. One can access BIOS through Setup Utility.


A bit is the basic data unit of all digital computers. The bit is an abbreviation for binary digits like 0 or 1. A single bit can be used to control ON/OFF functions. Bits are the basic unit of information volume on a computer storage device.

Bit density

The number of bits or binary digits that can be kept within a given storage area. It is also expressed as bits per inch, the number of bits that can be scripted onto one inch of track on a disk surface.


In an individual file record, a group of bytes is handled, stored, and accessed as a logical data unit. A block in a UNIX workstation is the smallest area that is put together that can be assigned for data storage.


It is the way you restart your computer. It all reloads your operating system to a fresh start.


It determines the quantity of information on a hard drive. It is an abbreviation for Bits per inch.


When there are variations in data processing rates between sender and receiver, a short-term memory storage area is used to compensate for it. A disk buffer is an implanted memory in a hard disk drive that acts as a barrier between the rest of the computer and the physical hard disk platter used for storage.

Buffer Bandwidth

Speed of moving data to or from the buffer. The data is processed per second by a discreet GPU (Graphics processing unit).

Burst Mode Transfer Rate: The speed at which the data is moved into the buffer RAM of the hard disk within a short period. It usually takes minutes or seconds and is usually defined as speed in Mbps. Burst mode data transfer speed can be three to four times faster than standard transmission protocols.


A byte is a unit of data eight binary digits long. The storage capacity of a hard drive is calculated in megabytes, the total number of retainable bits divided by eight million. Individual bytes can hold a string of bits that needs to be used in a larger unit for application purposes.



It is hardware or software that aims to store short-term data in a computing environment. It is a speedy and costly memory used to enhance the performance of regularly accessed data. When data is read from a disk, a copy is saved in the cache accompanied by its disk address. The cache checks whether the addresses of reading operations are already in the cache. If it is present, the data go back instantly. If the addresses are not present in the cache, it affirms that the address is grabbed from the disk and saved in the cache.


Quantity of information saved on a hard drive is calculated in bytes. It is also known as storage capacity. It is measured in gigabytes and terabytes.


It is a connection on the motherboard or controller card. A motherboard contains two channels, namely primary and secondary channels. t is necessary to add a secondary channel if your motherboard has only a primary channel. A controller card is needed to generate a secondary channel.

Channel Assembly

The final system gathering by the distributor from equipment provided by the manufacturer and from things shipped directly to the assembler in the computer industry is known as Channel Assembly.


It can be defined as a group of sectors. It is also an allocation unit in a hard drive. Despite the file's size, one cluster is devoted to each file. During the formatting process, the cluster size increases with the partition size. Wasting space on small files can be eluded if one can create numerous smaller partitions.

CMOS Setup

It is a program found in most systems that helps you to configure internal and external devices. It also powers up one's laptop's BIOS firmware, which is responsible for starting your computer and forming data flow.

Command Aging

The Small Computer System Interface (SCSI) feature removes the command reordering algorithm from keeping I/O configurations waiting in the command queue for extended periods.

Command Queuing

It is an aspect that permits the hard drive to receive I/O processes from multiple initiators and implement them in a proper sequence of events.

Command Reordering

Here, the drives change the order of I/O processes in the command queue, which paves the way to reduce the seek time and rotational latency. However, it also increases the amount of material passing through a system.


It is a tool that transmits information between a computer and its remote devices. It also acts as a traffic manager. A hard disk controller is an electronic device found in a computer hard disk that helps the processor to read, write, delete and alter data to and from a hard disk. Interface controllers have been changed to serial interfaces to meet the demand of transferring high-speed data.

Controller Card

It is usually established in a bus slot in the computer. It is an adapter with control electronics for multiple hard drives. It is usually installed on a motherboard to connect and control parts of a computer like hard drives, disk drives, and other input devices. Each part of the hardware needs a controller for its smooth functioning.

Correctable Error

It is an error that a hard drive can rectify using the Error Detection and Correction strategy.

Customer Configuration Code (CCC)

A firmware tracking code that describes massive product changes. When form, fit, or function changes are executed, this number increases. The CCC code ensures that the correct alteration of the drive product reaches its clients.

Cyclic Redundancy Check (C.R.C.)

It is a method used to detect defects in digital networks and storage devices to identify accidental modifications to digital data. By measuring the C.R.C. data and comparing it with the original data sent, the receiver can identify some errors during data transmission.


There are 1,024 cylinders present on a hard disk. The pile of platters turns at a particular speed. The top of the cylinder is created by identical track numbers on vertically piled disks.

Cylinder, Head, Sector (C.H.S.) Addressing

It is a computer access mode that allows addresses to information on computer hard drives. Nowadays, this mode is replaced with E.C.H.S. and L.B.A. It also recognizes each part of a disk by identifying where they are located in a track, and the track is confirmed by the head and cylinder numbers. All the individual blocks on the drive contain a one-of-a-kind cylinder, head, and sector.



The primary function of a database is to store file data in the database to redeem it faster. It can also be defined as a group of data stored on a computer, such as a hard drive, CD-ROM, etc., which can be used for multiple intentions.

Data Synchronizer

The role of a data synchronizer is to guarantee flawless, safe, amendable data and customer experience. With the arrival of data in a hard drive is cleansed and checked for faults, duplication, and steadiness before it can be put to use. It synchronizes information between multiple devices and updates changes on its own between them to maintain accuracy within systems.

Dedicated Landing Zone

Inside a hard disk, a particular part of the disk's surface where no information is stored and where the read or write head is placed where it stays stationary is called a dedicated landing zone. It also ensures that the magnetized part of the disk remains safe and uncorrupted data movement. It also ensures that the read or write heads are stored without contact with the data cylinders when the power to the drive is off.

Defect Free

Hard drives usually do not wear off when not in use for an extended period as they are made of magnetic fields. So defect-free is defined as recording surfaces that do not contain any identifiable deficiencies.

Defect Management

It is defined as removing data errors on a recording surface by negating bad sectors. The defect tables are built into the drive itself and are used to determine the bad sectors encountered when the drive is made initially. One cannot access the defective areas, so when data is imprinted onto a disk, it gets stored in error-free zones.


It is a program that keeps the operating system, applications, and data files like documents, pictures, music, etc. The other elements in your P.C. come together to show you the application and files stored in your drive. We can alter the location of files in the desktop folder, anywhere on the hard drive, or to a different computer on the network.

Differential SCSI

It is mainly used for applications that need a long cable length of up to 30 meters. It is an electrical signal setup that uses multiple lines for transmitting the information. It is also a kind of connection used for storage in a computer. SCSI also means ports and cables used to connect various types of hard drives, optical drives, scanners, and other devices to a computer. These devices also use Single-Ended, Low Voltage Differential electric interfaces between the device and host adapter. One wire is used for each data with a corresponding ground wire for that signal.

Direct Memory Access (D.M.A.)

D.M.A. transmits information straight to and from the primary memory without traveling through the CPU. The system can pursue CPU processing while it transmits data to/ from the hard drive, thus upgrading its rate and capability. The process is managed by a chip known as D.M.A. Controller.


It is a part of a computer's RAM kept apart for holding data that has been read from a disk for a short period. It is a magnetic storage medium for a computer. Unlike a RAM disk, the disk cache does not hold all the files. Instead, it usually holds data that has been requested from a disk lately.

Disk Controller

It is a chip that manages the transmission or access of information between disk and buffer.

Disk Drive Controller

A hard disk drive controller contains a disk controller and interface controller.

Disk Operating System (D.O.S.)

A computer program provides a file system for organizing information, writing files, and processing on a storage disk.

Disk Transfer Rate

The rate at which information is transmitted to and from a disk platter. It has an advancing range of disk transmission speed from the inner diameter to the outer diameter of the disk. However, the drive works with rotating disks, and the transmission speed is limited to 100 Mbps to 200 Mbps.


E.C.C. On-the-Fly

It is a hardware developing strategy that modifies faults in the read buffer previous to host transmission, excluding performance fines. The fault corrections are not seen in a host system because they do not require help from the drive's firmware.

E.I.D.E. (Enhanced Integrated Drive Electronics)

The first interface a desktop computer uses is to control the connection between hard drives and the central processing unit. The interface performs as a negotiator between the computer and the storage device.

Embedded Servo Control

It is a servo configuration used on hard disks. It initiates precise and faultless feedback data to the head position servo system, which does not need an entire data space as servo control information is contained on every surface.


During encoding, data patterns are developed before scripting them onto a data surface. It arranges a series of characters, like letters, numbers, punctuation symbols, etc., into a specialized format for methodical transfer.


A sequence of computers engaged primarily in high-volume domains with multiple users, such as servers or networking applications. It contains individual user workstations needed in demanding design, engineering, and audio or visual applications.

Enterprise Storage Group

There are three kinds of enterprise storage, namely Direct Attached Storage (D.A.S.), Network Attached Storage (N.A.S.), or Storage Area Network (SAN). Enterprise drives are created to toil in workstations, servers, and storage devices.

Error Correction Code (E.C.C.)

It is a mathematical algorithm that discovers and amends all the faults in a data field. It encrypts information so a decoder can find and correct faults in the data.

Error Log

It is a file that collects cases of critical errors and failures faced by an operating system, application, or server. An error log may contain errors like hardware or software failures, table and configuration corruption, etc. Error logs can also be used as handy material for troubleshooting and controlling. 

Error Rate

The number of errors that happens while reading a particular number of bits. It is the proportion of faulty units to the total number of units transferred.

Extended Partition

Numerous partitions can be created on one primary partition and multiple expanded partitions on a hard disk. The operating system files must stay on the primary partition. In an expanded partition, files other than D.O.S. or operating system files can be contained on a disk.


F.A.T. (File Allocation Table)

It is a file system created for hard drives that use 12 to 16 bits for every cluster entry into the file allocation table. An operating system also uses it to govern specific files present in a hard drive and other operating systems. It is also a data table used to keep file information and elongate the existence of a hard drive.


It is a utility that permits altering the partitioning of one's hard drive. It is present in all the versions of MS-DOS and Windows operating systems.


It is the procedure of redeeming information in an operating system. It occurs continuously from the moment a computer starts up till it shuts down.

Fibre Channel (F.C.)

It is a coherent set of standards created by an ANSI-approved X3 group. This set of standards elucidates up-to-date settlements for ductile data transfer. Fibre Channel embraces three topologies: point-to-point, arbitrated loop, and fabric. It is also mainly used for users in servers that use drives with Fibre Channel 40-pin "SCA-2" hot pluggable backplane.

Fibre Channel Arbitrated Loop (FC-AL)

A group of high-speed fiber channel network systems linkage that connects devices using loop topology. It is a consecutive storage interface created to understand the requirements and demands of high-end applications.


It can be interpreted as indefinite directives or instructions set up directly into the circuitry read-only memory for guiding the functions of the computer. A Firmware is hard-coded into the hard drive, thus allowing the hardware to create a connection with the software.

F.I.T. (Functional Integrity Testing)

It is a group of tests contained in a hard drive to assure its harmony with hosts, operating systems, adapters, application programs, and peripherals. It must be noted that this testing must be implemented before the product is disclosed to manufacturing.  

Flow Control

It is the administration of transferring data between two devices, such as nodes in a network or between the CPU and its surrounding devices. It alerts the sending device to slow down or speed up data transfer because of the device's capacity to match it. It also helps devices with less speed to commune with high-speed devices and the other way around.


The procedure that gets the hard drive ready to store information. Low-level formatting creates the areas of sectors so that the user data can be kept safe in them. Thus, formatting deletes all the data on a hard drive and prepares the file system required for collecting and receiving files.

Formatted Capacity

The amount of storage space required to store data in a large storage unit. Formatted capacity is the total capacity negated by the capacity consumed by the overhead data needed for formatting the media. Simply put, it can be defined as the total number of bytes present to be scripted after a device has been formatted for usage.

Form Factor

The tangible and superficial features of a particular device


A communication convention that allows the concurrent transfer of data and receptions in both channel directions. Full-duplex is used when communication from two devices is always needed.


G.B. (Gigabyte)

A unit of data storage capacity is equal to 1 billion bytes. One thousand Megabytes is equivalent to one Gigabyte.

Giant MR (GMR)

The primary implementation of GMR is in magnetic field sensors. It is used to understand data in hard disk drives and other devices.



A communication strategy that allows transferring data in two directions, but the transmission occurs only in one direction. The two devices can transfer and accept data, so while one device sends data, the other receives it.

Half-height Drives

An internal disk drive includes hard drives with a length of 1.0 inches and 1.6 inches. The height of a Half-height drive is 1.6 inches.

Hard Drive

The electromagnetic device that one can use to contain operating systems, software programs, and multiple files using magnetic disks. It manages and guides the reading and writing of the hard drive that supplies data storage. It is used as a primary or secondary storage device in a P.C.

Hard Drive Industry

It is a sector that is a combination of hard drive creators.

Hard Error

A problem in RAM paves the way to an enduring physical flaw resulting from a hardware defect. It is an error that repeats every time the exact area on a disk is examined.

Hard Sectored

A methodology that uses digital signals to stipulate the initiation of a sector on a track.


It is defined as a read or write head which is a tiny electromagnetic coil and metal pole which modifies the platter's magnetic fields into electrical current. A drive with numerous platters will have dedicated heads for each data surface.

Head Actuator

A device moves a hard drive's head to straighten read or write heads to read and write information.

Head Crash

Refers to the physical damage that happens when the read or write head meets with the disk surface or the spinning platter. The read or write head is above the spinning platter so that any contact can cause significant destruction to the disk's surface.

Head Disk Assembly (HDA)

It can be defined as the mechanical elements of a hard drive like a platter, read or write arm, spindle motor, actuators, etc.

Head Loading Zone

It is a space on the disk that is mainly kept for the heads to use when taking off or landing when the power to the drive is disabled. In the head loading zone, information is not saved.

Head Stack Assembly

It refers to the inside of a hard drive where numerous platters are piled upon each other. It is a mechanism consisting of a read or writes heads on the surface and beneath each platter where data is scripted.

Headerless Format

The insufficiency of header or I.D. fields ensures high format effectiveness and increased user magnitude.

High-Level Format

It is referred to as quick formatting as it is a fast operation where vacant file systems are set up for storing and receiving new data. A high-level format should be implemented on a new hard drive before it can be used.


It is a host computer to which the rest of the computers and the surrounding devices are connected.

Host Adapter

It is also known as the host controller and is a plug-in board that permits communication with devices like hard drives, fiber, USB, etc. It also behaves as an interface between the computer system bus and disk drive.  

Host Interface

A hard disk interface can be defined as the relation between the host computer system and the hard disk. Its primary obligation is to transfer information between the hard disk cache and the host memory. Various hard disk interfaces dictate the speed of data transfer between the hard disk and the computer.

Host Transfer Rate

The rate at which the host computer can transmit information across the SCSI or E.I.D.E. interface. They are limited to a transfer speed of 100 Mbps to 200 Mbps.


IDE (Integrated Drive Electronics)

Hard drives with IDE are the ones that have the interface controller electronics integrated into the hard drive design rather than as a separate device. It is also defined as the connection between a computer's motherboard and a disk storage device.

Index Pulse Signal

It is a sign of the beginning of a disk revolution by a digital pulse signal. After indexing, a servo pattern or the pre-recorded data is found on the disk.


It sends commands to a target via the SCSI bus. Although most SCSI devices are either initiators or targets, some devices can perform both functions.

Input: It is the data received by the computer, such as commands from the user, and processed by it.

Input/output (I/O)

It is a hardware device capable of receiving inputted, outputted, or other processed data. It also can receive information as input sent to a computer.


A hardware or software convention that controls information interchange between the device and the computer. To satisfy the requirements for high-speed data transmission, the interfaces of hard drives have been altered to serial interfaces. The primary interfaces you can find in a hard drive are the Fibre Channel (F.C.), Serial A.T.A. (SATA), and Serial Attached SCSI (S.A.S.).

Interface controller

Here, computer data is interpreted through a circuit, and it instructs into a structure fitted for use by the hard drive. It also manages the transmission of information between the host and the buffer.


It is the organization of sectors on a track. It is also an approach to enhance slow system performance in block storage devices like a hard disk by keeping information accessed, in a particular order, into sector blocks.


It is an alert sent by a subsystem to a CPU that points out whether a process has been finished or not. It cues the operating system to conclude the work on one process and to initiate work on another.


As used in I.B.M. PCs and A.T.s during the 1980s, Industry Standard Architecture (I.S.A.) is the 16-bit internal bus used in computers based on the Intel 80286 and its recent descendants. Several I.B.M. PC compatibles and PC/XT models were (essentially) backward compatible with the 8-bit bus of the 8088-based I.B.M. PC.



An E.I.D.E. jumper connects the pins on the circuit board on the hard drive jumper block electronically by placing electrically conductive elements over them. For example, the jumper can choose a slave or master hard drive. It is situated near the 40-pin connector on the hard drive.

Just-in-time (J.I.T.)

It is used in many industries to create hard drives. It is a production and inventory control methodology in which several elements are sent to an assembly point as required.


Kilobyte (K.B.)

Referred to as a unit of 1000 bytes, a kilobyte is equivalent to 2 10 or 1024 bytes in computer memory, which is divided into quantities that are powers of two.


Landing Zone

When instructed to do so or when the power is switched off, the read/write heads migrate to this spot on the inner part of the disc. This region of the disc is not used to store user data.

Laser Textured Media: It limits the corrosion and resistance in a hard drive. Newer model hard drives are robust because of the accuracy and stability of laser zone texturing.


The time it takes for the read/write heads to wait for the disc to turn to the proper position before they can access the necessary data. The average time between the head getting on track and the data moving to the head for a disc rotating at 5200 RPM is 5.8 milliseconds.

Local Area Network (LAN)

It is a method in which computer users in a similar organization are connected and are regular to the centrally-stored multitude of information in LAN servers.

Logical Address

A data request from a controller is made using a storage location address, which may not indicate the actual location. The controller translates the request from a logical to a physical address to obtain the data from a specific physical place on the storage device.

L.B.A. (Logical Block Addressing)

It is a technique for identifying the drive's sectors. It replaces the cylinder, head, and sector addresses with a single collection of logical block numbers to address the drive's sectors. Accessing larger drives than is typically possible using C.H.S. addressing is made possible by this.

Logical Drive

A logical drive is a portion of the hard disc that, in a directory structure, seems to be a distinct drive. On a hard drive's expanded partition, logical drives are created. The first three letters of the 26 letters for logical drives are retained. So, on your extended partition, you can construct up to 23 logical drives. Typically, logical drives are used to arrange directories and files.

Logistics Model

Businesses use a method to plan their physical product delivery. A hard drive manufacturer's business plan may include sales to distributors, retail chains, O.E.M. clients, or a combination.

Low-level formatting

It is the process of generating sectors on the disc surface, allowing the operating system to use the areas required to build the file structure. High-end technical data centers or manufacturing facilities frequently carry out low-level formatting. However, in most cases, a customer usually doesn't need to low-level format a hard drive.

Low profile (L.P.)

Hard drives using the 3.5-inch standard are available in 1.0-inch and 1.6-inch heights. Hard drives that are low-profile are one inch tall.


Magnetic flux: The quantity of magnetic field lines allowed to pass through a specific closed surface is known as the magnetic flux. It offers an estimate of the entire magnetic field that covers a particular surface area. It can also be defined as the arrangement of the bit's magnetic pole directions when they are written to the disc.


It is the first drive in a twin-drive setup. A single drive is a master drive that functions independently without slave drives. The primary accessible drive directly connected to the IDE connector from the computer's motherboard is the master (primary) hard disc. The master hard drive is the first device the motherboard will attempt to access when you turn on your computer.


A removable device, such as an external HDD or USB flash drive, or one built inside a computing system, like an S.S.D., can serve as a storage medium. Magnetic tape, C.D.s, and non-volatile memory (NVM) cards are some examples of different storage media. The discs with their magnetic coatings in hard drives are occasionally referred to as the coating material.

M.B. (Megabyte)

A megabyte is defined as one million bytes. Hard disc storage space has increased significantly in recent years. Hard drives with a 5-megabyte capacity were the first to be made available for personal computers.

Mechanical Latencies

It consists of rotational latency as well as seek time. The primary barrier to increasing performance in hard drives is mechanical latencies. Mechanical latencies are more time-consuming than electronic (non-mechanical) latencies involved in data transmission. 


It is a system or device that can both keep and access information. Storage space on the hard drive is abundant and ranges from 1 G.B. to 1TB. RAM stores information momentarily. The data are momentarily downloaded to the RAM when a user attempts to access certain information on the Internet. The user's downloaded data from the Internet is securely kept on the hard drive.

M.F.M. (Multiple Frequency Modulation)

Modified Frequency Modulation, or M.F.M. for short, is a technique for erasing blank spaces from magnetic media like tapes and discs to capture digital data. Compared to the prior recording technique, the data-encoding scheme doubles the amount of storage.

M.R. Heads (Magneto-resistive Heads)

These were created to boost area density and enhance drive performance. As opposed to conventional inductive thin-film read-write heads, M.R. heads use distinct read and write elements. M.R. heads use a separate magneto-resistive element for reading data and an inductive element for writing data. Data recorded on the disk drive surface is detected by a magnetically sensitive substance in the read element. M.R. head design produces a stronger message than inductive thin-film read-write heads, allowing it to read data with a higher area density. A typical thin-film inductive element writes data to the drive because the magneto-resistive element can only read data.

MTBF (Mean Time Between Failures)

The MTBF is calculated by dividing the total failures by the total operating hours of the component. The reliability of the equipment increases with the period between failures.

M.T.T.R. (Mean Time to Repair)

The typical amount of time needed to fix a drive in the field. Only large subassemblies (the P.C.B., sealed housing, etc.) are changed in the field apart from component-level repairs, as these are not functioning in the field.


A concurrent presentation of information in multiple media, such as auditory and visual.


A system in information technology that permits several users to access data simultaneously.


Network Computer

A particular computer can only interact with a central data storage facility, like a server or RAID system, and has restricted data storage.


Operating System

It is software that facilitates communication between computer hardware, such as a hard drive, and the user and applications running on your system.



It is a logical method of partitioning a hard drive so that an operating system views each division as a different hard drive. A different drive letter is assigned to each partition.

Passive Termination

It is a termination architecture that employs a voltage divider network of passive resistors to match the frequency at the end of the SCSI bus.


A personal computer is a multifunctional microcomputer that is affordable, practical, and small enough for individual usage.

Personal Storage Division: A group of techniques and technologies used to record and store digital data on magnetic, optical, or silicon-based storage mediums.


It is a fundamental concept from which various goods are created and made.

Platter: An actual platter installed inside a fixed-disk drive made of metal or stiff material. Many drives are made up of numerous platters stacked on the spindle to increase the amount of data storage surfaces available. Each platter may hold data on one or both surfaces.


A socket or connection on the controller card or motherboard. One or two ports may be on a motherboard (primary and secondary). You might need to add a controller card to generate a second port if your motherboard only has one port.


It is queued instructions that are loaded into a processor's external bus during transient states.

Primary Partition

It is a technique for conceptually dividing a hard drive so that an operating system sees each partition as a different hard drive. The drive letter for each partition is different.


It is a data transfer methodology that establishes time, control format, and data representation.

P.R.M.L. (Partial Response Maximum Likelihood)

It is a technique used in computer data storage to extract digital information from a weak analog read-back signal captured by the head of a magnetic storage device or tape drive. It is a read channel that precisely retrieves user data from the drive using sampled data, active equalization, and Viterbi detection.

Programmed I/O

In this method, data flow between the system and the disk drive is directly managed by the system CPU and supporting hardware. The terms "programmed I/O modes" or, more popularly, "P.I.O. modes" refer to the various programmed I/O speeds.

Proximity Recording

It is a recording method that permits the read/write head near the disk surface, increasing recording frequency.



A procedure used to evaluate potential system components for suitability and usefulness.


It is a data model known as first-in-first-out (FIFO) that is used to order multiple requests for a resource, such as a printer, processor, or communications channel. The host moves items from the front of the queue and adds them to the back.


Radial Path

It is defined as the direct line that runs through the disk's center and out to its periphery.

Random Access Memory (RAM)

It is a memory that, unlike sequential access devices like tape drives, permits access to any storage location at any time. The CPU only handles the fastest data access possible since the RAM is quick and data is moved from the hard drive to RAM.

Read Channel

It carries out data conversions and encoding. The drive must accurately write computer-generated information to a magnetic medium and reread it.

Read Verify

It is a method of checking the accuracy of data that involves reading data from the drive to the controller, which checks the data for errors but does not send it on to the system.

Read/Write Head

A hard disk's read/write head is a particular physical component in charge of both reading data from and writing data to the drive. Typically, read/write heads consist of an actuator arm and a narrow horizontal magnetic blade.

Recoverable Error

It is a read error that the device can fix by performing an E.C.C. recovery operation or by rereading the data.

Redundant Arrays of Independent Disks (RAID)

It is a technique for protecting data in the event of a drive failure by storing the same data in several locations on numerous disk drives or solid-state drives (S.S.D.s). However, there are several RAID levels, and not all of them aim to provide durability.

RLL (Run Length Limited)

It is currently the most common hard drive encoding system and can fit twice as much information on a single drive as M.F.M. and three times as information as F.M. In RLL encoding, the drive merges sets of bits into a single unit to produce particular flux reversal patterns.

Rotational Latency

The period is taken to get data from a disk because it rotates. The typical rotational latency for a disk rotating at 5200 RPM is 5.8 milliseconds.

R.P.M. (Revolutions per Minute)

The spindle speed is another name for the disk's spinning speed. Usually, hard drives rotate at a fixed pace. The mechanical latencies increase as R.P.M. decreases. Disk R.P.M. significantly impacts rotational delay, making it a crucial factor in hard drive performance.



The SCA-2 (Single Connector Attach) interface has choices for backplane connectors for SCSI devices as well as a grounding contact, blind mate connector, direct plug misalignment tolerance, ESD protection, and hot swap functionality. The 80-pin SCSI connector is also known as SCA-2.

Small Computer System Interface (SCSI)

A connection point for peripheral controllers and computers. It is widely used in Apple Macintosh systems in business computing. Enhanced Integrated Drive Electronics, more commonly known as E.I.D.E., is the same interface system found in most personal computers.

SCSI Configure Automatically (SCAM)

It enables consumers to attach SCSI devices without having to bother about installation choices.


It is a 512-byte data packet used by SCSI and E.I.D.E. hard drives. The host interface can only read or write this smallest quantity of information to the drive. Sectors are typically combined into blocks or logical blocks on Macintosh and Unix drives, which are the lowest data unit allowed. The phrases block and sector are occasionally considered alike because these blocks are frequently classified as a single sector. 

Sector Slipping

It keeps the data in chronological order during a format or transfer process by pushing down problematic sector sites. The drive contains Spares all over for this reason.


It can be defined as a read/write headset being moved to a specified spot. The actuator transfers the heads to the cylinder holding the data storage sector and track.

Seek Time

It can measure the hard drive's read/write head's transit time to the desired location in milliseconds.

Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.)

It is a technique that helps users to avoid potential system breakdowns caused by hard drive failure by making an effort to predict impending hard drive failure before it happens.

Sequential Access

The sequential reading or writing of data instead of random access. Blocks of data are sequentially stored using magnetic tape drives.

Serial Storage Architecture (S.A.A.)

The umbrella term for a series of standards created by an X3 organization with ANSI approval. The group of specifications establishes a new serial connection with dynamic add/drop functionality.


It is a computer system with access to shared resources mainly used to store data. A server includes an operating system for networks.

Servo Burst

It delivers positional data to the actuator arm, which can be found embedded in or covering an entire disk surface at regular intervals.

Single-ended SCSI

It is a SCSI's standard electrical interface. A single-ended interface has one signal and one ground line for each SCSI signal. It is mainly used when cables less than 19 feet are needed.


It is a dual drive combination's second drive.

Soft Error

This mistake does not surface while rereading the same spot.

Soft Sectored

It is a method that enables the controller to locate the start of a sector by reading the disk's format data.


They are the Primary Commands for SCSI. The design of storage devices can be very flexible, but all SCSI targets must implement the following four commands: INQUIRY, READ CAPACITY, REQUEST SENSE, and TEST UNIT READY.


The central, rod-like axle holds the disks in place. One statistic used to assess the performance of disk drives is spindle speed, expressed in rotations per minute (R.P.M.).

Spindle Motor

The spindle motors in hard drives move the disks. These components are crucial to the performance of hard drives since the accuracy of these motors dictates the capacity and speed of hard disk drives.

Spindle Speed

It can be described as the disk's rotational speed. When sequential operations and rotational latency are used, the data can be read from the disk more quickly. Additionally, a shorter wait time for the correct sector number to pass beneath the head improves random operations. Because of this, there has been a desire to speed up the spindle motor.

Spindle Synchronization

This feature rotates SCSI hard disks in systems with numerous drives simultaneously to the same address position.

Storage Capacity

It is the volume of information that a hard drive can hold.


It is a subsidiary or constituent element of a system, such as the hard disk of a personal computer.


The portion of a platter is coated with magnetic material for data recording, either on the top or bottom. A portion or both of a platter's surfaces may be used to hold data.

Synchronous Transmission

It is a transfer in which a correction device maintains the desired phase connection between the transmitting and receiving devices. In contrast, the devices constantly operate at the same frequency.

System Files

Data is organized, transmitted, and received to a hard drive partition using file systems. Additionally, they define an index and the kinds of information that can be included in a file.


Tagged Queuing

A feature included in some A.T.A. and SCSI hard disks. It enables a hard drive to receive numerous read and write requests from the operating system.

Task File

It is the group of I/O Host Interface Registers that the E.I.D.E. interface uses to communicate status, commands, and data with the drive.

Thin Client Architecture

It is a computer system in which data is centrally kept, and only a tiny amount of storage space is available at different points of use. Thin clients operate by remotely connecting to a server-based computing environment, where most applications, confidential information, and memory are kept.

T.P.I. (Tracks per inch)

The number of tracks written within each inch of the disk's surface is used to evaluate how tightly the tracks are packed on the disk's surface. It also goes by the name "track density".


It is a disk surface with a concentric magnetic circle pattern utilized for data storage and reading. As employed in the Cylinder-Head-Record (C.C.H.H.R.) addressing mode of a CKD disc, a track is a physical division of data in a disk drive.

Track-to-track Seek Time

It is the time required for the drive's head assembly to read/write data to a specific sector of the disk after the actuator arm, to which the heads are attached, is correctly positioned on the track, where the data is stored.

Transfer Rate

It is the speed at which the controller delivers and receives data to and from the hard drive. To accurately represent drive performance, processing, head swaps, and searches are all considered while calculating the transfer rate. Since it only applies to data transfer into RAM, the burst mode transfer rate differs from the transfer rate.

Translating BIOS

It is a BIOS for the system that permits access to E.I.D.E. drives more significant than 528 MB. In this configuration, the BIOS uses the logical geometry supplied by the disk directly without translating at the BIOS level.


Ultra SCSI

It offers 40 MB/s transmissions over a 16-bit Wide SCSI bus or 20 MB/s transfers over an 8-bit bus. This functionality, also known as Fast-20 SCSI, is most frequently seen in SCSI-3 drives.

Ultra D.M.A./33

It is a high-speed host data transfer function with a 33.3 MB per second data transfer rate. It is a method for transmitting information from a hard drive to the computer's random access memory via the data paths of the computer.

Unformatted Capacity

It is the entire amount of disk space that can be used, taking into account the space needed to store location, boundary definitions, and servo data.

Unrecoverable Error

It can be defined as a read error that cannot be fixed using an Error Correction Code (E.C.C.) technique or by rereading the data when server retries are activated.

Untagged Queuing

The drive can take one I/O request from each initiator at the most.


It is impossible to upgrade an existing drive because it cannot be given more space. The ways to expand a computer's storage area are by either replacing an existing drive or adding a new drive. As a result, it swaps out a hard drive for one with more capacity, performance, or both.


Viterbi Detection

A methodology used in reading channel technology that accurately detects data written on a disk by detecting an entire sequence of data bits at a time. It determines the most likely sequence of data bits by comparing the actual sequence of data bit samples with sequences of possible data bit samples.

Voice Coil

Since the device is an actuator motor, the head moves in direct proportion to the force applied by the magnetic rotating voice coil.


Winchester Disk

It is the traditional name for a hard drive. The name Winchester is derived from a first-generation I.B.M. disk drive with 30 M.B. of fixed capacity and 30 M.B. of detachable storage.


Windows is a collection of different exclusive graphical operating system versions created and promoted by Microsoft.


It is a personal computer with great storage and processing power mainly used for engineering, design, and audiovisual applications that require quick access to data and the capability to alter it in complex ways.


It is the process of capturing flux reversals on a disk's magnetic surface.

Write Cache

Here, data transport from the host to the hard drive is buffered using fast RAM.

Write Verify

A drive with the Write Verify functionality will confirm that it can read the data it just wrote on the drive, and after writing, it makes sure that it can access the data later. If the drive fails to analyze the information, it attempts to verify the data again by writing it to another location on the drive.


Zoned Recording

This methodology uses more sectors per track to expand the amount of hard drive space that is accessible. It also enables the outer ways to have more sectors than the inner tracks by increasing the sectors per track.


Most people who lead a digital lifestyle face stress when they lose data. You could accidentally delete files or empty your computer's recycle bin in several situations. So, it is crucial to comprehend and be familiar with words used in hard drive data recovery. So, the majority of related terminology covered in this glossary with detailed explanations should help you grasp the technical aspects of the subject.

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