External hard disk drive

Seagate FreeAgent Go external hard disk drive.

An external hard disk drive is a type of hard disk drive which is externally connected to a computer, and may be portable. External hard disk drives are connected to the computer using a cable which is compatible with Small Computer System Interface (SCSI), Integrated Drive Electronics (IDE), Universal Serial Bus (USB), IEEE 1394 (Firewire), CAT-3 or CAT-5 cable (Ethernet), eSATA or other bus standards.

History

Main article: History of hard disk drives

The first commercial hard disks were large and cumbersome, and were not stored within the computer itself so therefore fits within the definition external hard disk. The hard disk platters are stored within protective covers or memory units, which sits outside. These hard disks were soon evolved to be compact enough that the disks were able to be mounted into bays inside a computer.

By the end of 20th century, internal drives became the system of choice for computers running Windows, while external hard drives remained popular for much longer on the Apple Macintosh and other platforms. Every Mac made between 1986 and 1998 has a SCSI port on the back, making external expansion easy; also, "toaster" Macs did not have easily accessible hard drive bays (or, in the case of the Mac Plus, any hard drive bay at all), so on those models, external SCSI disks were the only reasonable option. These external drives, like the Apple ProFile are in no way as portable nor as compact as the modern ones for commercial use.

After the Internet has been introduced, more information and files needs to be stored than ever before, and more back-ups be made due to threats such as viruses. Once again, external hard drives are popular among users of all platforms.

Presently, the market for external hard disks are aimed towards portability, as well as a higher amount of memory. Currently the commercial external hard disks of the highest capacity are usually found at 1 TB or 1.5 TB from manufacturers such as Hitachi, SimpleTech, Western Digital, Seagate, CMS, Maxtor and LaCie

Structure and design

The internal structure of external hard disk drives is similar to normal hard disk drives; in fact, they include a normal hard disk drive which is mounted on a disk enclosure. For the same reason, high capacity external hard disk drives (which weigh more) were for a time less common, although external hard disk drives with more than 500 GB of storage capacity are now commonly manufactured.

Although external hard disk drives are aimed to be portable, the data cannot be secured on them due to their insufficient shock protection especially compared to digital portable media storage devices such flash memories and memory cards. Nonetheless, external hard disk drives cost less than memory cards or flash memories of the same storage, and are the only portable media storage options available in the size of hundreds of gigabytes.

File system, partition, and operating system

Most external hard drives are compatible with the three major operating systems: Windows, Mac OS (Unix), and Linux. On each of these OS's you have tools for disk formatting (and maybe journaling), and partitioning Also, you can install the operating system onto these hard drives, thus gaining the capability to boot into them and run programs or applications on a computer.

These external hard disks are also able to run different file systems, such as Mac OS X Extended (Journaled), FAT, and NTFS. The option of using different operating systems and file systems on different partitions

External hard disks can be partitioned and formatted using 'Disk Management Console' under Windows 2000, XP and Vista, 'Disk Utility' and 'BootCamp' under Mac OS X or 'Gparted' and 'Qtparted' under Linux.

Manufacturers of external hard disks/drives

Active manufacturers

The bright yellow LED panel on the end of the FreeAgent Go series pulsates when data is being read or copied to and from the drive.

These companies still manufacture hard disks and are in the international market.

(This list is not complete.)

• Addonics(Enclosures Only)
• Apple
• Bull
• Cavalry Storage
• CMS
• Dell
• Freecom
• Hitachi
• IBM
• Imitation Corp
• Iomega
• LaCie
• Maxwell
• Mtron (Korean)
• Optware
• Philips
• Plextor
• QNAP
• Seagate and Maxtor (the latter was acquired by the former in 2006)
• SimpleTech
• Silicon Power
• SmallDrives
• STEC
• Toshiba
• Transcend
• Western Digital
• Verbatim

Former manufacturers

These manufacturers have manufactured external hard disks, but are currently not doing so

• Apple Inc.

See also

• GRUB
• Live distro
• Partition manager
• USB keydrive

External links

• PC Magazine reviews about external hard disk drives