Apart from being one of the most essential parts of your computer, hard
drive storage is constantly updating, in terms of both capacity of disk
space and in physical size. When it comes time to upgrade your disk
storage, there are a number of factors for you to take into account. Once
you've made basic decisions about size, connectivity, speed and data
transfer rate, and whether you want an internal drive or external.ATA (Basic). Supports up to two hard drives and features a
16-bit interface, handling transfer speeds up to 8.3 MB per second.
How A Hard Drive Works
Your hard drive has a number of magnetized platters connected to a
spindle. The spindle spins the platters at a very fast speed while a
series of read/write heads scan over them both looking for and writing
information. This information is transferred via a cable system, or
through a wireless connection to a hard disk controller, which in most
systems is built into the motherboard, or in some systems installed as an
add-in card. The information that comes from your hard drive through its
controller is then made available to the components of your computer. The
effectiveness of your hard drive (its performance) depends on how much of
its capacity remains unused, how well organized the data is (known as
fragmentation) and its data transfer rate, which in turn is dependent on
its connection type and the drive's spin rate.
Internal Hard Drives
Most computers from, the most basic home models up to the most powerful
servers, have an internally installed hard drive. Technology today ensures
that they are all generally fast, reliable, and offer dependable storage
ability. Most modern computers have installation slots and cabling to
enable you to install additional hard drive. This allows you to increase
your storage capacity without giving up your existing hard drive.
External Hard Drives
These drives are essentially the same drives as ones installed inside
computers, but cased inside a protective, portable case. This is a good
solution for people who work remotely and need to transport large amounts
of data. If an external hard drive is your choice, make sure your computer
is compatible with the interface that the hard drive uses. An add-in card,
such as a FireWire card can help to increase your computer's capabilities.
Laptop Hard Drives
There have been many advances in miniaturization of hardware components
for laptop computing, and hard drive technology is not left out of this
loop. Laptop hard drives function in exactly the same way as internal hard
drives on other computers, only they are designed to provide maximum
storage and efficiency in the smallest possible package. For added
flexibility, some laptop computers come with removable hard drives that
can be easily installed and removed. However, before you buy a hard drive
for your portable computer, check that the hard drive's specifications
will meet the standards of your computer, as many laptop hard drives are
proprietary, and are not compatible with other brands and models.
Your hard drive stores your operating system, its programs (games and
applications), your working data, and your digital music and movies. Most
new computer purchases have a minimum of 80 GB of hard disk space; many
have considerably more. Hard drive space is one of those things, once you
have it, you'll find ways to fill it soon enough. There is no real rule of
thumb, but consider the cost per gigabyte of storage as a way to guide
your purchase. If you work with large files, such as music, video and
graphics, it pays to have a big storage space for your work. It may pay
you to have two hard drives, one that houses all your programs and
applications, and another for storing your work and projects.
You may want to compare the price of say a 160GB drive against two
separate 80 GB drives. If one drive fails all is not lost. Today's hard
drives however, are fairly robust pieces of equipment and providing they
are not abuse, will serve you well for a long period of time.
One key distinguishing factor between hard drives is the way in which they
connect to your computer. There are a number of basic types of connection
schemes used with hard drives. Each connection type has a range of
differences in performance.
IDE (INTEGRATED DRIVE ELECTRONICS)
This is by the most common connection methods. Because the hard drive
controller is on the drive itself rather than on the motherboard, it helps
to keep costs down. There different IDE standards available. Mostly, you
will want to purchase the fastest possible standard that your computer can
support. Most computers will support a standard that is faster than what
the computer currently supports, so you can buy a faster drive, and update
your computer at a later time. The different IDE standards, in order from
most basic to fastest, are:
ATA-2 or EIDE (Enhanced IDE). Supports transfer speeds up to
13.3 MB per second.
ATA-3. A minor upgrade to ATA-2 and offers transfer speeds up
to 16.6 MB per second.
Ultra-ATA (Ultra-DMA, ATA-33 or DMA-33). Dramatic speed
improvements, with transfer rates up to 33 MB per second.
ATA-66. A version of ATA that doubles transfer rates up to 66
MB per second.
ATA-100. An upgrade to the ATA standard supporting transfer
rates up to 100 MB per second.
ATA-133. Found mostly in AMD-based systems (not supported by
Intel), with transfer rates up to 133 MB per second.
SCSI (SMALL COMPUTER SYSTEM INTERFACE)
This is the hard drive interface standard used by many high-end PCs,
networks and servers, and Apple Macintosh computers, except for the
earliest Macs and the newer iMacs. While some systems support SCSI
controllers on their motherboards, most feature a SCSI controller add-in
card. SCSI drives are usually faster and more reliable, and the SCSI
interface supports the connection of many more drives than IDE. While SCSI
drives come in many different standards, many of them are not compatible
with one another. So it's important be know that your computer supports
the drive you plan to install. The different SCSI connections are:
SCSI-1. A basic connection using a 25-pin connector, supporting
transfer rates up to 4 MB per second.
SCSI-2. Uses a 50-pin connector and supports multiple devices
with a transfer rate of 4MB per second.
Wide SCSI. These drives have a wider cable and a 68-pin
connection that supports 16-bit data transfers.
Fast SCSI. Uses an 8-bit bus but transfers data at 10 MB Per
Fast Wide SCSI. Doubles both the bus (16-bit) and the data
transfer rate (20 MB per second).
Ultra SCSI or Ultra Wide SCSI. Uses an 8-bit bus and transfers
data at 20 MB per second.
SCSI-3. Features a 16-bit bus and transfers data at 40 MB per
Ultra2 SCSI. Uses an 8-bit bus and transfer data at a rate of
40 MB per second.
Wide Ultra2 SCSI. Uses a 16-bit bus and supports data transfer
rates of 80 MB per second.
FIREWIRE (IEEE 1394)
The FireWire standard is becoming popular in portable hard drives because
it can be connected and removed without having to reboot the computer. It
supports data transfer rates of 50 MB per second, which means it is ideal
for video, audio and multimedia applications. FireWire requires a
dedicated add-in card and the hard drives in use require an external power
source, but the interface can support up to 63 devices simultaneously.
USB 1.1 (UNIVERSAL SERIAL BUS)
Pretty much all computers today include USB ports on their motherboards.
(On older model, you can install an add-in card.) USB controllers can be
used to connect external hard drives, and can support as many as 127
devices simultaneously either through USB port hubs or linked in a daisy
chain fashion. USB controllers do delivery power to devices connected to
them, but many hard drives still use an external power source. USB is
limited by its data transfer speed, the maximum rate being about at 1.5 MB
USB 2.0 (HI-SPEED USB)
A more recently introduced and far better connection standard that offers
backward compatibility and data transfer rates of up to 60 MB per second.
USB 1.1 system can use a USB 2.0 device; it will need a USB 2.0 controller
card to achieve the higher transfer rates.
Fibre Cabling is mainly used for high-bandwidth network servers and
workstations, providing very fast data transfer rates (up to 106MB per
second), and connection at long cabled distances, although it is expensive
and you need to install a special interface card.
Data transfer rate is crucial to how well your computer performs for you.
Apart from the connection types above, the performance of your hard drive
depends on its spin rate, measured in RPM. Higher RPM generally means
faster data transfer rate. The lowest spin speed that is acceptable in
computing today is 5400 RPM. The common standard at present is 7200 RPM.
But higher speeds are available in SCSI drives, and it is one area of
computer system technology that is constantly being developed.
A larger capacity hard drive will not necessarily make your system
function any faster unless you are low on available disk space with your
existing drive. But a drive with Ultra ATA/100 or ATA/133 and a 7200 RPM
spin rate will pretty much guarantee an improved hard drive performance.
Cache (pronounces 'cash') is additional temporary memory that acts as a
buffer between the system and the drive. Frequently accessed data is
stored in the cache for quick access. Cache sizes vary from 512 KB up to
16 MB on some SCSI drives. The larger cache you have on your drive, the
faster your drive will transfer data. If you are working with large files,
such as video, images and audio files, it pays to have the largest cache
you can get (8MB or more).
The data on your disk is stored in tracks and sectors and when you
instruct your hard drive controller to retrieve some data, it goes
looking. The seek time is a measure of how long it takes the hard drive to
find a specific track on a disk. Seek times can vary slightly from disk to
disk and a drive with a faster seek time will always perform better.
INTERNAL AND EXTERNAL TRANSFER RATES
These two rates tell how fast a drive actually reads the data and passes
it along to the system. Internal Transfer Rate refers to the time it takes
for a drives heads to read data from the platter and pass it to the
drive's cache. The External Transfer Rate (sometimes called the Transfer
Rate or the Burst Transfer Rate) is a measure of the time it takes to send
the data from the cache all the way to the computer's memory. Naturally
faster transfer rates provide better performance.
S.M.A.R.T. (Self-Monitoring Analysis and Reporting Technology)
This is a nice built-in feature in some hard drives that can help alert
you to a potential hardware problem. Your computer's BIOS must support
this in order for the SMART function it to work, however the drive itself
will still work in a system without it.