Hard Drives

Whatever you do with your computer -play computer games or run email software - the speed of the hard disk drive and its capacity seems to always have an impact on the processes and its always not enough speed or capacity.

There are some specifications you need to consider when buying hard drives. These are interface, rotation speed, and capacity.

Interface

There are three common interfaces of hard disk drives: SCSI, IDE and USB/Firewire.

SCSI (Small Computer System Interface). This interface is for very professional systems. If you are considering to use the computer as a network server, a SCSI is the best choice because it easily handles input from multiple users, devising the most efficient method of processing requests. However, this interface requires a SCSI controller card to be installed in order to connect SCSI peripheral devices.

Today, installing and setting up a SCSI controller and SCSI hard drives is not so difficult task as it may seems to be. If your system supports Plug and Play features and you get a Plug and Play SCSI controller, it takes literally minutes to setup SCSI devices. But keep in mind, while this interface lets your system to achieve better performance, it can burn a hole in your pocket.

IDE (Integrated Drive Electronics). This is the most popular and usable interface. It is defined by transfer modes called ATA (Advanced Technology Attachment). Today, there are two very popular transfer modes: Parallel ATA-100/133 and Serial ATA interfaces. 100/133 means that data transfer speed is 100 or 133 megabytes per second. Serial ATA supports transfers of 150 megabytes per second and is projected to scale up to 600 megabytes per second in coming years.

USB (Universal Serial Bus). The advantage to USB, including the ability to install peripherals while your computer is running, is the capability to attach up to 127 devices at a time (often referred to as daisy-chaining). However, USB transfers data at up to 12 megabytes per second. You'll find USB on most new computers, with the all popular operating systems supporting it.

Also, you may want to consider Firewire interface, the newest interface available. Firewire is a cross-platform version of the high-speed serial data bus that can move large amounts of data between your PC and peripherals. Firewire boasts transfer speeds of up to 400MB per second, and is included in many of the latest multimedia devices.

Rotation speed

Rotation speed of a hard drive is the speed at which its platters spin. This specification is measured in revolutions per minute (RPM). For the most ATA/USB/Firewire drives, there are two rotation speeds to consider: 5400 or 7200 rpm. For SCSI drives: 10,000 or 15,000 rpm. As you can see, the IDE drives are beaten by the SCSI ones. But keep in mind, for most home and small office users, IDE drives are the best choice because they offer comparable performance to SCSI for considerably less money. Most IDE hard drives cost less than SCSI ones and don't require the additional investment of a SCSI controller. Unless your PC is very very old, your computer should support up to four IDE drives with no additional hardware.

Capacity

Capacity or size of a hard drive is measured in gigabytes (GB). The very common advice is to buy a hard drive with a higher capacity you can afford. So if you store MP3s, photos and digital video, consider a drive up to 80GB or two smaller drives. Today, the common PC systems offer 20GB or 40GB drives.

When you do shopping for the hard disk you also may want to consider specifications such as access speed and buffer size.

Access speed

Access speed (or seek speed) is the speed at which a hard drive searches for particular data. It is measured in milliseconds (ms) and ranged from 9 ms and lower.

Buffer size

This is the amount of cache memory which is used to store recently read data which is being written to the disk. The latest hard drives for PC computers have sufficient buffer sizes from 2 to 8MB, more than enough for typical use.