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Selecting a hard drive
by John Anthony

Hard Disk size is measured in gigabytes GB (billions of bytes) and TB (trillion of bytes) for newer drives.
Like everything else in the PC world hard drive capacity continues to increase in size and large TB (terra-byte) drives are readily available.

The PC-XT released by IBM in 1980 had a 10Mb drive which would not hold a small fraction of any newer Windows operating system!

Hard drives are offered in two different technologies: the legacy standard electro-mechanical type and the newer Solid State Drive (SSD).

Additionally, they are offered in two form factors: the legacy internal type and the newer external type.

By Technology

Standard Drive
In a standard drive there are magnetic platters that spin around at 10,000 RPM (speeds of early drives were 5400 or 7200 RPM). Over each platter is a read/write head that can move back and forth across the platter like the tone arm of the turntable. The difference is the read/write head never touches the surface. When they do it is not by design and is called a head crash which ruins the hard drive!

When your PC wants to get a file from your hard drive, the read/write head has to move to the track that contains the file. The time it takes to get from where it is to the track location is called access time and is determined by the spin rate of the drive.

Once it is over the track it begins transferring data from the disk to the PC. The time it takes to transfer data is called the data transfer rate and is dependent on the electronics that actually read the data from the platter.

Access time and data transfer rate determine the drives performance.

Solid State Drive (SSD)
This drive first appeared in the mass market in the late 2000s.

They are made up of solid state flash memory chips on a circuit board.

There no rotating platters or read/write heads to wear out but the flash memory has a finite number of writes cycles.

Their maximum storage size is less than the maximum size of standard drives.

By Form Factor

Internal Drive
Internal drives are offered in two sizes 2-1/2 inch for laptops and 3-1/2 inch for desktops.

They are mounted inside the case of the computer and connect to the motherboard by SATA (Serial ATA), PATA (Parallel ATA), USB or SAS (Serial attached SCSI) cables.
SATA has become the dominant connection type.

External Drive
External drives with massive storage are readily available. For example, 1 TB $60, 4 TB $100.

They plug directly into any USB port on the computer. The operating system recognizes it and loads the appropriate driver which makes it an available drive to the PC.

To access the new drive, click My Computer(XP), Computer(7), This PC(10) and all drives are shown.
Your C:\ drive will be shown and the new external drive will be shown under it with a new drive letter.

You can easily copy folders and files to the new drive.

A 1 TB standard internal drive costs $60-$75, while an SSD internal 1 TB costs about $130-$150.
SSD have a speed advantage over standard drives. They boot up faster, launches apps faster, and generally has faster overall performance.
Since they have no moving parts SSDs are more durable and rugged.

Standard hard drives can become fragmented while SSD being completely solid state do not.

Standard hard drives with moving parts can only be made so small while SSDs with only memory chips on board can fit into smaller packages.

SSds make no noise at all. Even the smoothest standard drive makes some noise as it spins around. So which one really you need is matter of weighing all these factors and determine which one best meets your needs. rule

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