Data Recovery

All you need to know about hard disks: Reasons for Data Loss and Solutions Thereof

Summary: This comprehensive guide provides you with the latest information on different types of hard disks based on storage media & technology, interface standards, features, and more. The hard disks are invariably used to store data, which may get lost due to deletion, virus attack, corruption, and other reasons; we help you with a software-based method to recover the lost data. Download a free trial of the software from the link given below:

The data storage technology has evolved wondrously over the past few years. In a few years, we have managed to compress even 1 TB storage capacity in miniature SD cards – a stark change from the gigantic hard disks of the yore. Today, we have so many data storage options available such as USB flash drives and memory cards, which are reliable, cheap, and portable compared to traditional hard disk.

Although USB flash drives and Micro SD cards are all the rage today, laptops and computers rely on hard disks to store files such as photos, videos, files, documents, folders, etc. Hard disk indeed make for the most important and widely used storage device today and have grown smaller in size with a tremendous increase in the storage capacity.

There are two types of hard disks, based on the fundamental storage technology and media:

  • Hard Disk Drive (HDD): This is the traditional electromechanical storage drive that uses a magnetized platter as the data storage media. It comprises a head mounted on a motorized spindle arm that floats over the platter to read (retrieve) and write (store) the data.
  • Solid-State Drive (SSD): This is a more recent storage device that uses flash memory and an integrated circuit to store the data. Unlike HDD, the SSD doesn’t have any moving component, so it is physically more reliable. 

Though HDDs and SSDs differ in their fundamental make and functionality, they serve the same purpose, i.e., is data storage.

How these hard disks are different from each other in terms of functionality, storing & retrieving data at the mechanical and electronic level is what we will discuss in this guide! Read on to know the different types of hard disks and choose the storage device that is the best for you.

The Different Types of Hard Disks

Hard Disk Drives (HDDs)

Hard disk drives (HDD) have been a dominant type of storage device since the early days of computers. An HDD is an electro-mechanical data storage device that stores all the data, including photos, documents, software, applications, programs, etc. It uses magnetized platters – circular disks with magnetic coating – to store the digital data.

An intricate head assembly mounted on an actuator arm is used for reading (retrieving) and writing (storing) the data bytes on the platter. In hard disk drives, the data can be stored in any order, i.e., non-contiguous blocks or sectors and sequentially on the magnetic storage media.

The speed of the rotating platter can be as high as 15,000 revolutions per minute. The hard disk drives have become more popular over time as they provide a lot of storage memory (up to 16 TB on a single HDD) at a significantly lower cost than solid-state drives.

Nonetheless, be aware that these hard disks are prone to data loss due to several reasons such as accidental deletion, formatting, corruption, etc. Hence, we suggest you to use hard disk recovery tools and methods to recover your data.

Illustrating a damaged Hard Disk Drive
Learn easy methods for recovering data on hard drive.

Main Components of Hard Disk Drives (HDDs)

Typically the hard drives are composed of five major components, which are as follows:

1. Platter

Platters are the circular disks that store data inside the hard disk in an organized manner. They are consist of a magnetic surface to store files, folders, and other data permanently.  The data is stored on the platters in sectors, tracks, and cylinders for making it easier to find. On large-sized hard disk, multiple platters are used to upsurge the overall drive capacity.

2. Spindle

The spindle is responsible for keeping the platters in position and rotate them as and when required. The RPM (revolutions-per-minute) rating controls how quickly data can be written to and read from the hard disks. It keeps the platters at a fixed distance apart from allowing read/write arm for acquiring access.

3. Read/Write Arm

The read/write arm determines the read/write head's movement to do the actual reading and writing to the platters by converting the magnetic surface into an electric current. The arm guides the read/write head to position appropriately based on the data, which needs to be read/written. The read/write arm is also known as the head arm or actuator arm. Usually, there is one read/write head for every platter side, floating 3 to 20 millionths of an inch right above the platter surface

4. Actuator

The actuator or head actuator takes instruction from the drive's circuit board to determine the movement of the read/write arm and supervise the data transfer to and from the platters. The actuator is a small motor that makes sure that the read/write heads are positioned in precisely the right manner and place at all times.

5. Disk Controller

Disk controllers are responsible for responding to commands from subsystem initiators or the host. The hard drive's storage controller manages the execution of command within the drive to interoperate with the external initiator. The software component of the drive is called firmware. It is stored in e-prom chips in the hard drive’s circuit board. Additionally, the processor chips used as hard drive controllers are amended with extra memory and faster core.

Other Components

The other components of a hard disk drive include Servo control electronics, buffer memory, read/write channel, and front-end circuit board. Moreover, every hard drive has one port to transfer data and instructions to and from the rest of the system and one port for power supply.

Types of Hard Disk Drives Based on Interface Standard

Commonly, there are five types of hard disk drives, including PATA, Serial ATA, SCSI, SAS, and FATA. They are distinguished depending on their capacity, size, spindle speed, capacity, and hardware interface.

Even though the hard disk drives are great storage devices, they may fail out of improper use, frequent storage and deletion of data, excessive data storage, wear and tear, corrupted file system, and virus attack, etc. leading to data loss. Read more about hard drive recovery methods and tools to get back your data easily.

Five Major Hard Disk Drives: From the Origin to the Latest

Parallel ATA (PATA):

The earliest hard drives used Parallel ATA (Advanced Technology Attachment) or PATA, an Integrated Drive Electronics (IDE) standard to connect the hard drive to a computer. PATA uses AT Attachment Packet Interface (ATAPI) standards. It is based on parallel signaling technology, meaning that devices send data in multiple binary digits (bits) to the same direction simultaneously. The Parallel ATA used to be called ATA. However, when the SATA (Serial ATA) standard came into existence, it was retroactively named PATA (Parallel ATA).

PATA dates back to the 1980s, and the connections for its devices were created with 40-conductor ribbon cables. Later, these connections were supplanted by 80-conductors (40+40 on either side of the cable). They hold the capacity to transfer data in 16-bit pockets simultaneously. Usually, the 80-wired cable connectors will either be black, blue, or gray, while 40-wire cable connectors will only be black.

Serial ATA (SATA):

SATA, which stands for Serial ATA or Serial AT Attachment, connects and transfers data from hard disk drives to computers. It is a computer bus interface, responsible for hosting bus adapters to mass storage devices such as HDDs, optical drives, and SSDs. SATA hard drive consists of 07 pin connectors, and its cables are thinner and more flexible.

Being the PATA hard drives' successor, SATA emerged as the predominant interface for storage devices on the PC. SATA was announced in the year 2000 to offer multiple advantages over PATA. SATA 1 was released in the year 2003, SATA 11 in 2004, and following that, SATA interface 3.0 in 2009. The SATA interface 3.0 was followed by Revisions 3.2, 3.3 in 2011, and 2016 respectively.

Based on serial signaling technology, SATA hard disk drives connect to the PC’s motherboard via controller hardware. SATA controller is responsible for managing the flow of data. Setting the controller to Advanced Host Controller Interface (AHCI) offers higher performance and enables hot-swapping features on SATA drives.

Small Computer System Interface (SCSI):

Small Computer System Interface (SCSI) is similar to IDE hard drives. It is used to connect and transfer data between PC and peripheral devices such as printers, scanners, hard drives, and more. It can generally connect up to 16 peripheral devices using only a single bus, including one host adapter. The SCSI drive is one of the most commonly used hard drives and tape drives; it can be connected internally and externally.

Developed in the 1970s by American National Standards Institute (ANSI), SATA is based on a proprietary bus interface called Shugart Associates System Interface (SASI). SCSI, popularly pronounced scuzzy, is supported by all the major Operating Systems (OS). SCSI helped computers adopt a more straightforward, cheaper, and less cluttered form factor with a standard interfacing technology.

Earlier versions of SCSI connections used exclusively parallel interfaces like IDE hard drives, but later iterations enabled the serial connections that facilitated quick data transmission. The SCSI uses controllers to send and receive data and power to SCSI-enabled devices such as printers, hard drives, etc. These controllers are embedded on the motherboard or a host adapter inserted into an expansion slot on the motherboard.

Serial Attached SCSI (SAS):

Serial Attached SCSI or SAS is a point-to-point serial interface used to connect and transfer data to and from hard drives based on SCSI command sets. The SAS interface operates at up to 1200 MB/sec and the throughput up to 12 GB/sec. The hard disk drives connected via the SAS interface are referred to as one of the most suitable drives for accomplishing high-speed operations with multiple rewriting cycles.

The SAS replaces the Parallel SCSI bus technology, which first came into existence in the 1980s. The SAS hard drives come in two different types: 10K and 15K, and offer optional compatibility with SATA version 2 and later. The K refers to the rotational speed of the hard drive. The SAS hard drives are faster and tend to be used for enterprise computing such as e-commerce and banking transactions where high availability and high speed are essential.

The SAS drives have a Mean Time Between Failure (MTBF), which is estimated to be around 1.2 million hours. The SAS connectors are much smaller as compared to parallel SCSI connectors and come in different variants. From a physical perspective, the SAS cables can be up to 10 meters in length.

Fibre Attached Technology Adapted (FATA)

Fibre Attached Technology Adapted or FAT is essentially FC (Fibre Channel) attached disk drive consisting of dual porting similar to a regular FC disk drive. It is a low-cost ATA equipped with a small external converter, bridging the FC interface. It enables users to use the disks in the enterprise-class disk enclosure. It includes an altered interface, allowing it to be inserted into specific storage arrays without even a separate enclosure.

Learn how to get back data from NTFS hard drive?

Solid-State Drives (SSDs)

Solid State Drives or SSD are flash-based hard drives, using integrated circuit assemblies to store data persistently.  SSDs are the latest types of hard disks, which have no moving parts, making them less susceptible to failure. Instead of magnetic storage, SSDs use flash memory chips. They are now commonly used in high-end laptops.

The Solid-State Drive functions as a secondary stage in the hierarchy of system storage. It is a new-generation storage device, which is significantly faster than the older hard disk drives. The NAND Flash chip based SSD are designed with floating gate transistors (FGRs) to hold the electrical charge.  The FGR enables the SSD to retain the stored data even when it is not connected to the power source.

SSD or Solid-state Drives use three major types of memory – (i) Single, (ii) Multi, and (iii) Triple-level cells. The Single-level cells (SLC) can only hold one bit of data at a time, while the Multiple-level cells (MLC) can hold two bits of data per cell and have a larger storage capacity in the same physical space as SLC. Moreover, an additional wire can be used for making it compatible with the other devices.

Illustrating a damaged Solid State Drive
Though the SSDs are less prone to failure and have a great lifespan, they may become inaccessible or show unallocated due to file system corruption, virus, attack, or SSD errors, leading to data loss. However, you may fix the unallocated SSD and recover data using professional disk recovery software.

Major Components of Solid-State Drives (SSDs)

The SSD consists of two major components: a flash controller and NAND flash.

Flash Controller:

The SSD controller is optimized to deliver high read and write performance for both the random and sequential data requests. The SSD controller, which is also referred to as processor, consists of electronics, bridging the flash memory components to the SSD input/output interfaces.

NAND Flash:

The NAND flash requires less memory chip area per cell, enabling greater storage density with a lower cost per bit than NOR flash. The SSD NAND flash also has up to 10 times the endurance of the NOR flash. The NAND flash is quite similar to the other secondary storage devices such as optical media and hard disk and highly suitable for use in mass-storage devices such as Solid-State Drives (SSDs) and memory cards, USBs, etc. The Flash memory cards and SSDs use multiple NAND flash memory chips to store the data.

Check out the top 4 Mac disk management software for Solid State Drives.

What is the difference between SSD and HDD?

The Hard disk drives is an old-school storage device, using mechanical platters and a moving read/write head for accessing the data, while SSD is the latest and faster type of device, storing data on instantly-accessible NAND flash memory chips. You may compare these storage media devices based upon several parameters. Here, we have created a comparison table to help you differentiate both of them and choose the best one as per your needs.

FeaturesHard Disk Drives (HDDs)Solid-State Drives (SSDs)
TechnologySerial signaling technologyParallel signaling technology
Read and write speeds7200 RPM HDD will deliver the speed of 80-160MB/stypical SSD will deliver the speed between 200 MB/s to 550 MB/s
CapacityUp to 16 TBUp to 100 TB
Moving partsComprises moving partsNo moving part
Mean Time Between Failure (MTBF)500,000 hours2.5 million hours
Energy EfficiencyConsumes more powerConsumes less power
Lifespan3-5 years (Average)Around 10 years
Ideal forLong-term data retentionShort-term data retention, or for storing data for a limited timeframe

Apart from the Hard Disk Drive and Solid-State Drives, the Hybrid Hard Drives gives you the benefits of both the HDDs and SSDs.

Hybrid Hard Drives

Hybrid Hard Drives or HHD, also known as Solid-State Hybrid Drives (SSHD) is a mass storage device used to store and process data. It is a combination of HDD and SSD, uses platters and flash memory. These drives deliver some of the performance of a solid-state drive and hold a mechanical drive capacity. They store the most frequently access data to the flash memory, enabling faster speed on these files while rest is stored on the platter.

The HHDs are quicker than a typical mechanical drive and faster than an SSD. The solid-state drive portion of the hybrid drive acts as a ‘cache’ consisting of the files you frequently access, such as your system or program files. However, this cache persists across reboots and speeds up your startup progress. The drive acts as a single drive to the system and handles the storage operation itself, without needing to shuffle files around or decide what data goes where.

Note: Like other hard disks, the Hybrid Hard Drives are also prone to data loss. The reasons could be different as explained in this article. To get back your data, you may use a disk recovery tool.

Which hard disk drive to choose?

Though all the storage devices serve the same purpose, data storing and retrieving, but based upon their storage capacity, technology, lifespan, etc., HDDs and SSDs are different.

The Hard Disk Drives (HDDs) are electro-mechanical storage drives, commonly used as the main storage drives in the computers. These drives use magnetism to store and retrieve data. While Solid-State Drives (SSDs) are the flash based storage drives that operates as the secondary storage in the hierarchy of the computer storage. These drives use NAND Flash memory, which allows SSDs to match the performance and capacity of HDDs.

While choosing between the HDDs and SSDs, you may want to consider the lifespan, storage capacity, speed, and several other factors. The HDDs are cheaper than SSDs and can offer you more storage space. However, SSDs are expensive but faster, use less energy and are more durable.

Moreover, you also have Hybrid Hard Drives (HHD) or Solid-State Hybrid Drive (SSHD), as an option. These drives provide the performance of solid-state drive and capacity of mechanical hard disk drives. Affordable for a huge storage space, also make them ideal to use for everyone.

You may compare the drives based upon their storage capacity, lifespan, speed, price and several other factors and choose the one most suitable to your needs.

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