Interpreting the purpose and working of HDD and SSD!!!

5 min readJan 17, 2024

HDD: -

The hard disk drive (HDD) is the main and the largest, data storage device in a PC. The operating system, application software and many other files are stored in the hard drives. Hard disk drive is also known as hard drive, hard disk, fixed disk, fixed drive or fixed disk drive. The data on hard drives can be erased or overwritten, the hard drive is classed as a non-volatile storage device which means it (unlike RAM).

HDDs were first introduced by IBM in 1956. They were initially used in data centers and mainframe computers. Over time, as the technology advanced and costs reduced, HDDs became more widely used in personal computers and laptops. Today, you can find HDDs in various electronic devices, including desktop computers, laptops, gaming consoles, and more.

Types of Interfaces

Parallel Advanced Technology Attachment (PATA): — The PATA interfaces we first introduced to the market by Compaq and Western Digital in 1986. They can have up to 80GB capacity and transfer data as fast as 133MB/s. The name ‘parallel’ comes from the fact that PATA interfaces can send and receive multiple data signals at the same time, in parallel. PATA interfaces are also known as Integrated Drive Electronics (IDE).
Serial Advanced Technology Attachment (SATA): -In recent times, Desktop and laptops ditched bulky PATA drives for slim, power-friendly SATA for better size, price and even speed. It connects to a computer like PATA but use serial signaling, transferring data one bit at a time. SATA interfaces transmit data at 150–300 MB/s, have thinner cables, and a 1-meter cable limit, providing significant advantages over PATA interfaces.
Small Computer System Interface (SCSI): — SCSI interface is an upgrade over SATA and PATA interfaces for many reasons such as round-the-clock operations, speed, storage, and several others. SCSI hard drives use a small computer system interface for connection. SCSI allows connection of devices like printers, scanners and hard drives with a data rate of 320MB/s and can be used internally or externally. SCSI connections on personal computers were replaced by USB, making SCSI obsolete for consumer hardware.

NVMe (Non-volatile Memory Express): — NVMe takes storage speed to the next level, handling demanding tasks effortlessly. Because of its high performance and scalability, you’ll find it mostly in data centers and newer computers. There are SSDs using the NVMe interface.

Its Advantages: -

i. lower power consumption

ii. multiple command queues

iii. reduced latency and input/output overhead — leading to better performance.

iv. utilization of CPU to full potential

Disadvantage is NVMe expensive than other storage options.

How a hard drive works:

· Platters store data in concentric circles (tracks) and pie-shaped slices (sectors).

· Tracks slice a hard drive, sectors subdivide those tracks, holding fixed data chunks (like 512 bytes). These chunks sometimes group into clusters for efficiency.

· Low-level formatting lays out the drive’s physical storage structure, while high-level formatting creates the file system for organizing data.

SSD: -

A solid-state drive (SSD) ditch spinning disks for flash memory chips, giving your computer lightning-fast data access compared to clunky had driven. Think no moving parts, just pure speed- boot and load programs in a blink!

· NAND flash memory chips organize data in blocks (grids) of pages (sectors), each storing 1–4 bits per cell. SLCs prioritize speed and reliability, QLCs focus on affordability, and each grid can store 256kb to 4MB of data.

· Early SSD ancestors, like magnetic core and CCROS, popped up in the 50s alongside vacuum tube computers. These fast memory helpers lost out to cheaper drum storage but laid the groundwork for the future of SSDs.

· Supercomputers in the 70s/80s boasted early SSDs, but sky-high costs kept them a rare sight.

· Pioneering the future, General Instruments built an early flash-like memory chip called EAROM in the late 70s.

· Benefits of using a solid-state drive (SSD): -

Faster speeds: -SSDs are much faster than HDDs. No clunky gears, just flash.
Durability: — Since SSDs don’t have any moving parts, they are more durable than HDDs. This makes them a better choice for laptops and other portable devices.
Energy Efficiency: — SSDs are more energy-efficient than HDDs. This is because they don’t need to spin up the platters or move the read/write head, which can consume a lot of power.
Quiet Operation: — because they don’t have any moving parts, SSDs operate silently.
Compact Size: — SSDs are smaller and lighter than HDDs, making them a good choice for devices where space is at a premium.

· Disadvantages of using a solid-state drive (SSD): -

Limited Lifespan: SSDs have a limited number of write cycles. This means that after a certain number of writes, the cells in the SSD can no longer be used.
Cost: SSDs are typically more expensive than hard disk drives (HDDs).
Capacity: While SSDs are available in larger capacities than ever before, they still can’t match the capacities of HDDs.
Performance Impact: As an SSD fills up, it can suffer from performance issues. This is because the drive needs to perform garbage collection and wear levelling, which can slow down the drive.
Data Recovery: If an SSD fails, it can be more difficult to recover the data. This is because of the way that SSDs write data to the drive.

How do solid-state drives (SSD) work?

-> Unlike spiny hard drives, SSDs rely on chip tech that keeps your data safe and sound, even when unplugged.

-> SSDs need to tidy up before reusing space. Deleting files just marks them for cleanup, so the operating system sends a “TRIM” command to trigger a “garbage collection” that erases data in blocks.

-> At 70% capacity, SSDs rearrange files to work around worn-out blocks, slowing performance temporarily.

-> Like stretching out a workout, wear levelling balances data writes across an SSD’s blocks, giving each cell its fair share of rest and maximizing the drive’s lifespan.