| Apart from being one of the most essential parts of | | | | Macintosh computers, except for the earliest Macs |
| your computer, hard drive storage is constantly | | | | and the newer iMacs. While some systems support |
| updating, in terms of both capacity of disk space and | | | | SCSI controllers on their motherboards, most feature a |
| in physical size. When it comes time to upgrade your | | | | SCSI controller add-in card. SCSI drives are usually |
| disk storage, there are a number of factors for you to | | | | faster and more reliable, and the SCSI interface |
| take into account. Once you've made basic decisions | | | | supports the connection of many more drives than |
| about size, connectivity, speed and data transfer rate, | | | | IDE. While SCSI drives come in many different |
| and whether you want an internal drive or external, | | | | standards, many of them are not compatible with one |
| you can search through au to find the most suitable | | | | another. So it's important be know that your computer |
| brand, and model, and compare the prices of different | | | | supports the drive you plan to install. The different |
| vendors. | | | | SCSI connections are: |
| Hard Drives | | | | SCSI-1. A basic connection using a 25-pin connector, |
| How A Hard Drive Works | | | | supporting transfer rates up to 4 MB per second. |
| Your hard drive has a number of magnetized platters | | | | SCSI-2. Uses a 50-pin connector and supports multiple |
| connected to a spindle. The spindle spins the platters | | | | devices with a transfer rate of 4MB per second. |
| at a very fast speed while a series of read/write | | | | Wide SCSI. These drives have a wider cable and a |
| heads scan over them both looking for and writing | | | | 68-pin connection that supports 16-bit data transfers. |
| information. This information is transferred via a cable | | | | Fast SCSI. Uses an 8-bit bus but transfers data at 10 |
| system, or through a wireless connection to a hard | | | | MB Per second. |
| disk controller, which in most systems is built into the | | | | Fast Wide SCSI. Doubles both the bus (16-bit) and the |
| motherboard, or in some systems installed as an add-in | | | | data transfer rate (20 MB per second). |
| card. The information that comes from your hard drive | | | | Ultra SCSI or Ultra Wide SCSI. Uses an 8-bit bus and |
| through its controller is then made available to the | | | | transfers data at 20 MB per second. |
| components of your computer. The effectiveness of | | | | SCSI-3. Features a 16-bit bus and transfers data at 40 |
| your hard drive (its performance) depends on how | | | | MB per second. |
| much of its capacity remains unused, how well | | | | Ultra2 SCSI. Uses an 8-bit bus and transfer data at a |
| organised the data is (known as fragmentation) and its | | | | rate of 40 MB per second. |
| data transfer rate, which in turn is dependent on its | | | | Wide Ultra2 SCSI. Uses a 16-bit bus and supports data |
| connection type and the drive's spin rate. | | | | transfer rates of 80 MB per second. |
| Internal Hard Drives | | | | SCSI Hard Drives |
| Most computers from, the most basic home models | | | | Ultra320 SCSI Hard Drives |
| up to the most powerful servers, have an internally | | | | FIREWIRE (IEEE 1394) |
| installed hard drive. Technology today ensures that | | | | The FireWire standard is becoming popular in portable |
| they are all generally fast, reliable, and offer | | | | hard drives because it can be connected and |
| dependable storage ability. Most modern computers | | | | removed without having to reboot the computer. It |
| have installation slots and cabling to enable you to | | | | supports data transfer rates of 50 MB per second, |
| install additional hard drive. This allows you to increase | | | | which means it is ideal for video, audio and multimedia |
| your storage capacity without giving up your existing | | | | applications. FireWire requires a dedicated add-in card |
| hard drive. | | | | and the hard drives in use require an external power |
| Internal Hard Drives | | | | source, but the interface can support up to 63 devices |
| External Hard Drives | | | | simultaneously. |
| These drives are essentially the same drives as ones | | | | FireWire Hard Drives |
| installed inside computers, but cased inside a protective, | | | | USB 1.1 (UNIVERSAL SERIAL BUS) |
| portable case. This is a good solution for people who | | | | Pretty much all computers today include USB ports on |
| work remotely and need to transport large amounts of | | | | their motherboards. (On older model, you can install an |
| data. If an external hard drive is your choice, make | | | | add-in card.) USB controllers can be used to connect |
| sure your computer is compatible with the interface | | | | external hard drives, and can support as many as 127 |
| that the hard drive uses. An add-in card, such as a | | | | devices simultaneously either through USB port hubs or |
| FireWire card can help to increase your computer's | | | | linked in a daisy chain fashion. USB controllers do |
| capabilities. You can compare different brands of | | | | delivery power to devices connected to them, but |
| external hard drives simply at au and search on the | | | | many hard drives still use an external power source. |
| connection type, or other specifications. | | | | USB is limited by its data transfer speed, the maximum |
| External Hard drives | | | | rate being about at 1.5 MB per second. |
| Laptop Hard Drives | | | | USB Hard Drives |
| There have been many advances in miniaturization of | | | | USB 2.0 (HI-SPEED USB) |
| hardware components for laptop computing, and hard | | | | A more recently introduced and far better connection |
| drive technology is not left out of this loop. Laptop hard | | | | standard that offers backward compatibility and data |
| drives function in exactly the same way as internal | | | | transfer rates of up to 60 MB per second. USB 1.1 |
| hard drives on other computers, only they are | | | | system can use a USB 2.0 device; it will need a USB |
| designed to provide maximum storage and efficiency | | | | 2.0 controller card to achieve the higher transfer rates. |
| in the smallest possible package. For added flexibility, | | | | USB 2.0 Hard Drives |
| some laptop computers come with removable hard | | | | FIBRE CHANNEL |
| drives that can be easily installed and removed. | | | | Fibre Cabling is mainly used for high-bandwidth |
| However, before you buy a hard drive for your | | | | network servers and workstations, providing very fast |
| portable computer, check that the hard drive's | | | | data transfer rates (up to 106MB per second), and |
| specifications will meet the standards of your | | | | connection at long cabled distances, although it is |
| computer, as many laptop hard drives are proprietary, | | | | expensive and you need to install a special interface |
| and are not compatible with other brands and models. | | | | card. |
| Laptop Hard Drives | | | | Spin rate |
| Size | | | | Data transfer rate is crucial to how well your computer |
| Your hard drive stores your operating system, its | | | | performs for you. Apart from the connection types |
| programs (games and applications), your working data, | | | | above, the performance of your hard drive depends |
| and your digital music and movies. Most new computer | | | | on its spin rate, measured in RPM. Higher RPM |
| purchases have a minimum of 80 GB of hard disk | | | | generally means faster data transfer rate. The lowest |
| space; many have considerably more. Hard drive | | | | spin speed that is acceptable in computing today is |
| space is one of those things, once you have it, you'll | | | | 5400 RPM. The common standard at present is 7200 |
| find ways to fill it soon enough. There is no real rule of | | | | RPM. But higher speeds are available in SCSI drives, |
| thumb, but consider the cost per gigabyte of storage | | | | and it is one area of computer system technology that |
| as a way to guide your purchase. If you work with | | | | is constantly being developed. |
| large files, such as music, video and graphics, it pays to | | | | 3600 RPM Hard Drives |
| have a big storage space for your work. It may pay | | | | 4200 RPM Hard Drives |
| you to have two hard drives, one that houses all your | | | | 5400 RPM Hard Drives |
| programs and applications, and another for storing your | | | | 7200 RPM Hard Drives |
| work and projects. | | | | 10000 RPM Hard Drives |
| You may want to compare the price of say a 160GB | | | | 15000 RPM Hard Drives |
| drive against two separate 80 GB drives. If one drive | | | | A larger capacity hard drive will not necessarily make |
| fails all is not lost. Today's hard drives however, are | | | | your system function any faster unless you are low on |
| fairly robust pieces of equipment and providing they | | | | available disk space with your existing drive. But a |
| are not abuse, will serve you well for a long period of | | | | drive with Ultra ATA/100 or ATA/133 and a 7200 |
| time.up to 32 GB Hard Drives | | | | RPM spin rate will pretty much guarantee an improved |
| 32-64 GB Hard Drives | | | | hard drive performance. |
| 64-100 GB Hard Drives | | | | Other considerations |
| 100 GB and more Hard Drives | | | | CACHE |
| Interface | | | | Cache (pronounces 'cash') is additional temporary |
| One key distinguishing factor between hard drives is | | | | memory that acts as a buffer between the system |
| the way in which they connect to your computer. | | | | and the drive. Frequently accessed data is stored in |
| There are a number of basic types of connection | | | | the cache for quick access. Cache sizes vary from |
| schemes used with hard drives. Each connection type | | | | 512 KB up to 16 MB on some SCSI drives. The larger |
| has a range of differences in performance. | | | | cache you have on your drive, the faster your drive |
| IDE (INTEGRATED DRIVE ELECTRONICS) | | | | will transfer data. If you are working with large files, |
| This is by the most common connection methods. | | | | such as video, images and audio files, it pays to have |
| Because the hard drive controller is on the drive itself | | | | the largest cache you can get (8MB or more). |
| rather than on the motherboard, it helps to keep costs | | | | SEEK TIME |
| down. There different IDE standards available. Mostly, | | | | The data on your disk is stored in tracks and sectors |
| you will want to purchase the fastest possible | | | | and when you instruct your hard drive controller to |
| standard that your computer can support. Most | | | | retrieve some data, it goes looking. The seek time is a |
| computers will support a standard that is faster than | | | | measure of how long it takes the hard drive to find a |
| what the computer currently supports, so you can buy | | | | specific track on a disk. Seek times can vary slightly |
| a faster drive, and update your computer at a later | | | | from disk to disk and a drive with a faster seek time |
| time. The different IDE standards, in order from most | | | | will always perform better. |
| basic to fastest, are: | | | | INTERNAL AND EXTERNAL TRANSFER RATES |
| ATA (Basic). Supports up to two hard drives and | | | | These two rates tell how fast a drive actually reads |
| features a 16-bit interface, handling transfer speeds up | | | | the data and passes it along to the system. Internal |
| to 8.3 MB per second. | | | | Transfer Rate refers to the time it takes for a drives |
| ATA-2 or EIDE (Enhanced IDE). Supports transfer | | | | heads to read data from the platter and pass it to the |
| speeds up to 13.3 MB per second. | | | | drive's cache. The External Transfer Rate (sometimes |
| ATA-3. A minor upgrade to ATA-2 and offers | | | | called the Transfer Rate or the Burst Transfer Rate) |
| transfer speeds up to 16.6 MB per second. | | | | is a measure of the time it takes to send the data |
| Ultra-ATA (Ultra-DMA, ATA-33 or DMA-33). Dramatic | | | | from the cache all the way to the computer's memory. |
| speed improvements, with transfer rates up to 33 MB | | | | Naturally faster transfer rates provide better |
| per second. | | | | performance. |
| ATA-66. A version of ATA that doubles transfer | | | | S.M.A.R.T. (Self-Monitoring Analysis and Reporting |
| rates up to 66 MB per second. | | | | Technology) |
| ATA-100. An upgrade to the ATA standard supporting | | | | This is a nice built-in feature in some hard drives that |
| transfer rates up to 100 MB per second. | | | | can help alert you to a potential hardware problem. |
| ATA-133. Found mostly in AMD-based systems (not | | | | Your computer's BIOS must support this in order for |
| supported by Intel), with transfer rates up to 133 MB | | | | the SMART function it to work, however the drive |
| per second. | | | | itself will still work in a system without it. |
| IDE / EIDE Hard Drives | | | | Buying and installing a hard drive has some technical |
| Serial ATA Hard Drives | | | | aspects that you need to take into account. Use au to |
| Ultra DMA 100 Hard Drives | | | | compare different hard drive makes and specifications |
| SCSI (SMALL COMPUTER SYSTEM INTERFACE) | | | | to find the drive that will work best for your needs and |
| This is the hard drive interface standard used by many | | | | computer. You can compare prices and service offers |
| high-end PCs, networks and servers, and Apple | | | | from different vendors. |