- Created on 05 August 2008
As computing becomes more data intensive, and files becomes more accessable through the internet, the number and size of files downloaded quickly overwhelmes the average hard drive (either desktop or laptop). Since the maximum size for optical storage(CD-R or DVD-R) is 8.5GB, it is generally not suitable for backing up large amount of data.
The best route for freeing up space on your main hard drive is by supplementing the system with an additional hard drive. Whereas it is relatively simple to install a secondary internal hard drive, most users opt for an external hard drive. The benefits are two fold: data (images, documents, video etc.) can be backed up and is easily transferred between machines with ease without a network. Also there is no impact on the thermal characteristics of a PC, i.e. it is not likely to overheat (adding additional components to a system can increase the overall heat output of a machine, therfore increasing the risk of component damage).
When puchasing an external hard drive there are two options:
Prebuilt external hard drives are available to purchase with a variety of connections that can simply be directly plugged in and used. This is a real benefit to those users who do not want the hastle of building a hard drive into an enclosure or the resulting partitioning and formatting. There is however a premium for this benefit, and the available products are limited.
Alternatively, external hard drive enclosures can be porchased separately from the hard drive component. This allows for the re-use of existing spare drives or the use of hard drives of choice. This way of purchasing an external hard drive allows for greater customisation and the diverse range of hard drive enclosures available give a great number of options in regards to design, interface and size:
There are two physical sizes of hard drives available for computing:
2.5" hard drives are used for laptops and the smaller external hard drives. The size limits the storage of the drive, but allows for greater portability and requires less power for function (therefore they can normally be powered from a USB port). The biggest 2.5" drive is manufactured by Fujitsu, with a storage capacity if 200GB.
3.5" hard drives are the more standard drive utilised in desktops and media center PCs. The increased size allows for greater storage capacity and currently the largest available 3.5" drive are 1TB. The increased capacity of the drives means that more power is required. Therefore the external 3.5" drives cannot be powered from USB alone and require additional power supplies.
Both 2.5" and 3.5 " hard drives come with two controller interfaces for connection:
IDE (Integrated Drive Electronics) / ATA/ATAPI (AT Attachment with Packet Interface) For many years this form of interface for hard drives was the main and cheapest option, until the advent of SATA. As such most computer up to 2003 had IDE/ATA drives installed, but this technology has now been superseded. The hard drive can still however be utilised from these older machines, and data accessed using hard drive enclosures with such an interface. The maximum speed of the IDE/ATAPI interface is 133MB/sec.
SATA (Serial Advanced Technology Attachment) SATA has superseded the IDE/ATAPI technology and is on revision II. The technology allows transfer speeds of up to 300 MB/sec. The other benefit of SATA drives is the ability to use eSATA (external SATA) with SATA compatibly motherboards. This means that the transfer rate of the hard drive is not limited to the connection between enclosure and PC, as it is with USB and potentially firewire.
There are four interfaces for data transfer between the hard drive enclosure and PC, and vary in their speed:
USB 2.0 (Universal Serial Bus) allows data transfer rates of up to 60 MB/sec.
Firewire 400 or Firewire 800 allow transfer rates of 50 MB/sec and 100 MB/sec respectively, although these interfaces require a compatible PC.
eSATA allows data transfer rates of up to 300 MB/sec, although it requires PC with an eSATA controller.
NAS (Network Attached Storage) generally come with a network interface capable of 10 MB/sec. However, they are not tied to one machine and can therefore be accessed by a number of machines on a network, making them ideal for sharing files. In addition, a lot of NAS enclosures come with an inbuilt bittorrent client that allows independant sharing of files without an attached computer.
USB and eSATA