Building a Computer for A+ Study Part V: The Hard Drive

Part five in a series on the basics of building a computer to prepare for the A+ certification exams.

The Hard Drive
A hard drive, also known as a hard disk drive or HDD, is the main and usually largest data storage device in a computer. The operating system, software, and other files are stored in the hard disk drive. The bigger the hard drive the more stuff you can fit on it. Since the hard drive is where all of your programs and files are stored, if the drive is damaged, you will possibly lose everything saved onto the computer. The hard drive in a computer can be either mechanical or solid state.

Mechanical Hard Drives
With a traditional mechanical HDD, data is stored on metal discs called platters. When you turn your computer on, the platters immediately begin to spin.  These platters spin around in order for the moving arm to read the magnetic data on the disc. The platters in a HDD typically get up to about 5,400 rotations per minute (rpm), but can run as high as 7,200 rpm (higher-end HDD can run at 10,000 rpm).

When your computer is on but you are not retrieving or writing anything to the memory, the platters in the HDD are always spinning. The arm with the heads on it, however, only begins to move when you run a program or open, save, or delete a file.
Solid-State Drives
A solid-state drive (SSD) is data storage that uses solid-state memory to store data on a computer. An SSD utilizes a special kind of memory chip with erasable, writeable cells that can hold data even when powered off like a USB flash drive (non-volatile NAND flash memory).
An SSD has many advantages over a mechanical hard drive. Being sold-state, the drive has no moving parts to malfunction and does not generate heat. Not having any moving parts decreases seek time significantly, thus making the SSD very fast. It is also more power efficient than a mechanical hard drive and completely silent. Finally, the SSD is more durable. If dropped or banged it isn’t as likely to be damaged compared to mechanical hard drives.
The downsides to SSD are that SSDs are more expensive compared to mechanical hard drives per gigabyte of storage and SSDs have a very limited number of writes before it fails, which is a trait shared by all flash based memory.
PATA vs SATA
PATA (top) & SATA (bottom)

Hard drives are connected to a computer using either PATA (Parallel Advanced Technology Attachment), also referred to as IDE, or SATA (Serial Advanced Technology Attachment).  When comparing PATA against SATA, SATA hard drives have several performance benefits that distinguish them from PATA hard drives. Most notably, SATA hard drives operate on higher bandwidths, which equates to faster data transfer.

It is easy to tell a SATA hard drive from an PATA hard drive by the much smaller and data and power connections used on the back of the two different hard drives. The cables that connect a SATA drive are much smaller than the regular, thick grey ribbons that connect PATA drives. PATA hard drives use a ribbon cable with 40 wires as opposed to a SATA cable which only has 7 wires.
What I picked
As I have expressed in some of my past articles, I am a huge fan of SSD. So naturally, I chose a SSD for this project. I picked the Kingston SSDNow 300V 120GB SSD. While it’s not the fastest SSD on the market, it’s 10x faster than a 7200 rpm mechanical HDD. It’s SATA Rev. 3.0 (6.0Gb/s) with both sequential reads and writes up to 450MB/s.
While the SSD will be used as the primary drive for the operating system and applications,  I also choose a 7,200 rpm 250GB WD Caviar Blue for additional storage capacity. Like the Kingston SSD, it supports 6.0Gb/s SATA speeds. WD Blue hard drives are known for delivering solid performance and reliability so it is a perfect choice to add more storage or if you decide to go solely with an HDD instead of an SSD.

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