Hard Drives
How a hard drive Works
Your hard disk has a series of magnetized plates connected to a spindle. Spindle spins the drums at a very fast speed while a series of read / writes heads scan over them both looking for and writing information. These data are transmitted over a cable system or via a wireless connection to a hard disk controller, which in most systems is built into the m
otherboard, or in some systems installed as an add-in card. The information comes from your hard drive through its controller is then made available to the components in your computer. Effectiveness of your hard drive (its performance) depends on how much of its capacity remains unused, how well organized data (known as fragmentation) and its data transfer speed, 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, so you can install additional hard drive. This allows you to increase your storage capacity without giving up your existing hard drive.
External hard disks
These drives are essentially the same drive as those installed in computers, but cased in a protective, portable case. It 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 to the hard drive uses. An add-in cards, such as a FireWire card can help to increase your computer's possibilities.
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 offer maximum storage and efficiency in the smallest possible package. For added flexibility, some laptop computers come with hard drives that can be easily installed and removed. But before you buy a hard drive to your laptop, make sure that the hard drive's specifications will meet the requirements for your computer, as many laptop hard drives are privately owned and are not compatible with other brands and models.
Size
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 at least 80 GB of hard disk space, many have considerably more. Hard drive space is one of those things when you have it, you'll find ways to fill it fast enough. There is no real rule of thumb, but consider the cost per gigabyte of storage space as a way to guide your purchase. If you work with large files such as music, video and graphics, it pays to have a large 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 wish 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 will be fairly robust equipment, and if not abuse, will serve you well for a long period.
up to 32 GB Hard Drives
32-64 GB Hard Drives
64-100 GB Hard Drives
100 GB Hard Drives and more
Interface
An important factor distinguishing hard disks is the way they connect to your computer. There are several basic types of connection schemes used with hard disk drives. Each connection type has a number of differences in outcomes.
IDE (Integrated Drive Electronics)
This is the most common methods. Because the hard disk controller is on the drive itself is on the motherboard, it helps to keep costs down. There different IDE standards available. Most of you will want to buy 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 date. The different IDE standards, in order from most basic to fastest, are:
ATA (Basic). Supports up to two hard drives and has a 16-bit interface, handling transfer speeds up to 8.3 MB per second.
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). Speed improvements, with transfer speeds 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 supports transfer speeds up to 100 MB per second.
ATA-133. Found mostly in the AMD-based systems (not supported by Intel), with transfer speeds up to 133 MB per second.
IDE / EIDE Hard Drives
Serial ATA hard drives
Ultra DMA 100 Hard Drives
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, with the exception of the earliest Macs and the new iMacs. While some systems support SCSI controllers on their motherboards, most feature a SCSI controller add-in cards. SCSI drives are usually faster and more reliable, and 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 each other. So it is important to know that your computer supports the drive you want to install. The different SCSI connections are:
SCSI-1. A basic connection using a 25-pin connector, supports transfer speeds up to 4 MB per second.
SCSI-2. Uses a 50-pin connector and supports multiple devices with a transfer rate of 4 MB per second.
Wide SCSI. These drives have a wider cable and a 68-pin connection that supports 16-bit data transfer.
Fast SCSI. Using an 8-bit bus but transfers data at 10 MB per second.
Fast Wide SCSI. Doubles both the bus (16-bit) and data transfer speed (20MB per second).
Ultra SCSI or Ultra Wide SCSI. Using an 8-bit bus and transfers data at 20 MB per second.
SCSI-3. Has a 16-bit bus and transfers data at 40 MB per second.
Ultra2 SCSI. Using an 8-bit bus and transfer data at speeds of 40 megabytes per second.
Wide Ultra2 SCSI. Uses a 16-bit bus and supports data transfer speeds of 80 MB per second.
SCSI hard drives
Ultra320 SCSI hard drives
FIREWIRE (IEEE 1394)
FireWire standard is becoming popular in portable hard drives because it can be connected and removed without restarting the computer. It supports data transfer speeds of 50 MB per second, which means that it is perfect for video, audio and multimedia applications. FireWire requires a dedicated add-in cards and hard drives in use require an external power source, but the interface can support up to 63 devices simultaneously.
FireWire Hard Drives
USB 1.1 (Universal Serial Bus)
Virtually all computers today include USB ports on their motherboards. (The 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 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, maximum speed is approximately at 1.5 MB per second.
USB hard drives
USB 2.0 (Hi-Speed USB)
A more recently introduced and far better connection standard that offers backward compatibility and transfer data at up to 60 MB per second. USB 1.1 system can use a USB 2.0 device, it will have a USB 2.0 controller card to reach higher transfer rates.
USB 2.0 Hard Drives
Fiber Channel
Fiber Cabling is mainly used for high-bandwidth networks, servers and workstations, which allows very fast data transfer (up to 106MB per second), and adherence to long cabled distances, although it is expensive, and you must install a special interface card.
Spin rate
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 speeds. 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 an area of computer system technology that is constantly evolving.
3600 rpm hard drives
4200 RPM Hard Drive
5400 RPM Hard Drive
7200 RPM Hard Drive
10,000 RPM Hard Drive
15,000 RPM Hard Drive
A larger capacity hard drive will not necessarily make your system faster, unless you're low on disk space on your hard drive with your existing drive. But a drive with Ultra ATA/100 or ATA/133 and a 7200 RPM spin rate will virtually guarantee a better hard drive performance.
Other Considerations
CACHE
Cache (pronounced "cash") are additional temporary memory that acts as a buffer between the system and drive. Frequently access data stored in cache for fast access. Cache size varies from 512 KB up to 16 MB on some SCSI drives. The larger cache you have on your hard drive, the faster your hard drive will transfer data. If you work with large files such as video, images and audio files, it pays to have the largest cache you can get (8MB or more).
Seek Time
Data on your disk is stored in tracks and sectors, and when you instruct your hard disk controller to retrieve some data, it goes out. The search time is a measure of how long it takes for the hard drive to find a specific track on a disc. Search times can vary slightly from disc to disc 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 transferred to the system. Internal Transfer Rate refers to the time it takes for a drives heads to read data from the dish, and pass them on to the drive cache. External Transfer Rate (sometimes called the Transfer Rate or the Burst Transfer Rate) is a measurement of the time it takes to send data from the cache all the way to the computer's memory. Naturally, faster transfer speeds give better results.
S.M.A.R.T. (Self-Monitoring Analysis and Reporting Technology)
This is a nice feature built into some hard disks that can help you out a potential hardware problem. BIOS must support this, for the SMART function it to work, but the drive itself will still work in a system without it.
Purchase and install a hard drive has some technical aspects that you must take into account.
