Hard disks are random access digital magnetic data storing devices. They have rotating rigid platters that have data magnetically read from or written to by read or write heads floating above the platters. Over the years, hard disk drives have decreased in price and size while increasing in capacity considerably. Hard disk drives have been the device principally used for storing secondary data in computers for a long time now. They have kept up with the requirements for secondary storage and therefore have survived the sweeping technology changes of the times. Today’s hard disk drives are often portable and operated on by high-speed serial interfaces. External removable hard disks or portable hard disks are popular now because they provide independence from system integration, and establish connection via options such as USB. The plug and play drive feature provides form system compatibility. Portable hard disk drives have the ability to function and allow themselves to be removed simply. They have impressive features like large capacities while maintaining a portable design. they are principally available in two basic physical sizes which are 2.5″ and 3.5″ . Owing to their flexible features, they are often used for such purposes as disk cloning that refers to the process of copying the contents of one hard disk to another via an ‘image file’ and to recover data. Prices having dropped considerably, it is not much of an issue to buy 1TB or 2TB portable hard drives. With lot of stress on eco-friendliness of technology, some companies such as Seagate claim to be environment friendly makers of hard drives. While it is true that portable hard disks are very efficient in moving and backing up data, the proliferation of such disks can be a threat to important data being stored in them.