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Tape Drives Technology and Hard Disks

Over time, technology has matured and cost has come down to very competitive levels. Despite the arrival of new-fangled technologies such as USB drives and digital video disks, it seems that hard drives and tape drives will be able to stand on their own at least for the next decade or so. Both of these have their own uses as well as strengths and weaknesses.

Hard Drives

Hard drives are unique devices in that they have for the last four decades maintained a total stranglehold on the primary storage market for computers and laptops. No other storage device such as USB drives or optical disks have been able to offer the kind of functionality and capacity that they offer for the purpose.

Hard drives come in the shape of small and air-tight metal boxes that are meant to be used as the main storage media for computers. They are also available as stand-alone devices (portable hard disks). Inside the box are a number of metal or glass platters which are coated with magnetic paint. It is this paint that acts as the data-recording surface. A read / write head (actually an electro-magnet) that is located at the end of an actuator arm accesses and modifies the data on the instructions of the operating system.

Hard drives are known for their phenomenal capacities. The ones commonly seen inside computers have a capacity of anywhere from 80 GB to 160 GB, though those with an astounding capacity of 500 GB and even 1 TB are also available. The hard drives can last for about five to seven years or about 25,000 hours of use. These are available in various interfaces such as SCSI, IDE and USB.

Tape Drives

Tape drives use a very old but tried and tested technology of magnetic storage. A tape drive system has two parts – the drive and cartridges. The latter are small plastic cases inside which exist two spools around which is wound a long and narrow length of magnetic tape. All data is recorded on one side of this tape by a read / write head that exists inside the drive. When a tape cartridge is inserted inside the drive, a motor begins to spin the spools, transferring the tape from one side to another. The tape runs brushing past the read / write head which has an electro-magnet installed over it.

Tape drives have for long been the media of choice for companies and businesses for taking backups of their data. This is because tapes are extremely reliable and cost-effective. They can be stored safely for a number of years and the cost per MB of data stored is one of the lowest compared to other devices. Tape drives can have capacities of 100 GB and above. Due to their low cost and high capacity, it seems that these are going to be in use for many more years to come.

Similarities

Tape drives and hard drives have many similarities. Both are among the oldest data storage devices to hit the market and have been around for decades. They are reliable and cost-effective. Both use magnetic technology to store data. A hard drive’s platters as well as a tape drive’s plastic tape have a coating of magnetic paint. The read / write head has an electromagnet that modifies the orientation of the magnetic particles on the recording surface to store and access digital data. Both the devices offer identical storage densities and continue to remain quite popular with computer users for a variety of uses.

Differences

There are substantial differences between tape drives and hard drives. The biggest one is in the kind of data access they offer. Tape drives have sequential data access. In this, if the operating system is looking for a particular file, the magnetic tape has to keep moving until the particular patch is reached where the data is residing. This process can take anywhere from several seconds to several minutes. Sequential access of tape drives makes them useless as primary storage devices for computers. They are instead good only for archival data storage where access speed doesn’t matter much.

Hard drives on the other hand offer random data access. This is because while in a tape drive, the head is fixed and stationary and only the tape moves brushing past it, in a hard drive, data-carrying platters as well as the head both are mobile. The entire data-recording surface is exposed to the head and it can move to any part of it to extract data instantly. This feature of hard drives coupled with their high storage capacity makes them ideal for use in computers as primary storage.

Article Source: http://www.dummiesguideto.com

James Walsh is a freelance writer and copy editor. If you are concerned about data loss and would like more information on Data Recovery see www.fields-data-recovery.co.uk

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