An external hard drive can be described in simple terms as a hard drive that is portable, or one that can be transported around. Although this is a very simple definition of what an external drive is, the truth is that, it is pretty much the same as it is described above. However, we can be more specific by describing it as the portable version of the fixed hard disk, which comes with a USB casing that enables it to be used on various computers with the help of an USB cable. Other than the above given differences, there is no noticeable difference between a fixed hard drive and an external hard disk. We can confirm this due to the presence of various moving parts that are present both in a fixed disk and an external disk.
The main purpose for which the external hard disk is used is also pretty much the same, which is data storage. However, in this case, the stored data can be transported along with the user and accessed on the computer of his choice. Some of the most common uses of the external disk are for storage of data, which usually eat up a lot of disk space on the hard disk. Some such data include movies, entire playlists, large number of photos, etc. However, the device is also used by many as a primary hard disk, which consist of the operating system. This is an advantage and a disadvantage of some sorts.
The problem with making the external hard disk, the primary drive, is that situations may arise when usage of the external hard disk in such a manner results in the secondary hard drive getting affected, and the user is unable to access the data on this drive . In such a scenario, the system boots in the right manner, but the data present on the secondary drives is inaccessible, which may sometimes lead to loss of data. A data recovery software is the only solution in such a situation, if the user needs to retrieve the lost data.
The user however, has to choose the external hard drive data recovery software based on the file system that has been used in the external hard drive. The user needs to determine whether NTFS or FAT file system has been used for formatting the external hard drive, and download the appropriate software to salvage the lost data.
Source by Susan George