When and Why to Use an External Hard Drive
Now that we have a basic understanding of external drives, the question is: when should they be used? Though they are a very easy and often times inexpensive way to store data they are by no means the correct choice for all circumstances.
The best use of an external hard drive is for storing data which is important enough to warranty special care but which does not require redundancy. An example can be anything which is valued but not so much that it is deemed "mission critical". This is so because if data is placed on one external drive the user is banking that that drive will not fail. Though because the external drive wil probably not be used as often the chance of failure decreases slightly. This makes an external drive a good place to store one's music collection, family photos, and documents, things which are important but may not warrant redundant storage. Also by placing this data in an external device, it is made portable so it can simply be plugged into another computer and made accessible.
Instead of storage, a better use for an external hard drive is backing up the local system. This can either be done manually or using a program, but a complete image of a local drive can be made on an external hard drive. This means a true, yet very easy back up system for the home. Because the data is on the local system's internal drive and the external, it is redundant and quite secure.
While the above remains to be true, some new consumer-level devices have started to change the rules a bit. Products like Netgear's Storage Central and Maxtor's OneTouch III Turbo are more than external hard drives, but don't exactly qualify as NAS or SAN devices. Both of these products function like external hard drives but they offer RAID options which can either speed up transfers (RAID 0) or enable data redundancy (RAID 1). These options offer the simplicity of an external hard drive, but the security of RAID. When using RAID 1, if one of the hard drives in the array were to fail the data on the remaining drive holds a complete copy, so the information is secure. While the cost of this is more than a standard external hard drive, the extra protection is certainly worth it to many users. This is going to leave users with a judgement to make, on just how much they want to protect their data and if the extra cost is worth it.
To sum things up, external hard drives are an effective, cheap, and easy way to store and even back up data. With a USB connection they can be used universally and they are hot-pluggable, while using a SATA connection will allow for very fast transfer rates and make it bootable, but will cut down on easy of use. Though an external hard drive is the preferred way to store data by consumers, its lack of redundancy can be a problem is it ever fails or is damaged in transit. For this reason it is ideal for backing up (where the data remains on the local machine) though truly redundant storage is only available externally when using a specialized device.