Importance of Data Storage - Part II

...Continued from Part-1

Magnetic Disk

Magnetic disk is the most popular medium for data storage. The greatest

advantage it offers over the tape media is that it has random access facility and thus

much higher data access speeds. As the capacity of magnetic disks is increasing

consistently over the past decade, this medium offers an ideal storage solution for the

desktop PC, network servers and WWW servers. Magnetic disks allow access to data - online

and to multiple users. Personal computers are currently being provided with hard disks of

up to 20GB capacity and Seagate currently offers hard disks of capacities up to 50GB for

server applications. Magnetic disks are, however, not portable, in that, they are fixed to

and operate with a given computer. Hence these are not suitable for physical data

distribution.

To further improve upon the access times of magnetic disks, a

configuration known as Redundant Array of Independent Disks (RAID) was developed at the

University of California, Berkeley. In this set up, several small capacity disks are

operated in parallel - a method found to reduce data access times compared to a single

disk of large capacity.

Optical Disks

Optical disks operate on the principle of writing and reading data

using a laser beam. At the time of writing, the laser beam creates 'pits' and 'lands' on

the recording material to represent the 1s and 0s. While reading, these 1s and 0s are read

back using a lower powered laser. The most popular form of optical disk is the Compact

Disc (CD) which offers about 650 MB of data on a single platter. It offers random access

to the stored data although its access time is inferior to that of a hard disk due to its

complicated head system incorporating laser source lens and mirrors. However, a major

advantage this medium has over the magnetic disk is that this is a removable medium - thus

rendering them ideally suited for physical data distribution. Enterprises can record

publicity information and product catalogues on this medium and use them for mailing to

its business associates. However, data which are not frequently changed are only to be

incorporated on to the CDs as creating CDs (master and duplicates) is an elaborate and

expensive process.

There are several 'intermediate' storage media technologies, which have

strived to capture the advantages of other technologies to render its own media more

competitive. Iomega's zip drive is a classical example. The zip drive offers removable

magnetic disk with much higher capacities than floppy disks (up to 250MB) yet retaining

the portability of a floppy disk. Thus, by offering fast access times and portability,

this can seriously challenge the optical disk media.

Digital Video Disk (or Digital Versatile Disk) - DVD - is another kind

of optical disk offering very high capacity storage (equivalent to that of tens of regular

CDs). These are primarily used for home entertainment and multimedia purposes but offer

good alternatives for long term data archiving as well.

Other technologies trying to make a mark include Storage Appliances

(network-based storage devices), holographic storage and Microprobe storage.

Storage technologies have come a long way since the days of paper tapes and punched

cards. However, saturation is not even in sight as new challenges are being posed

frequently. For example, it is estimated that devices connected to the World Wide Web hold

over five million terabytes of information. This figure can only increase and at a faster

pace than ever before. Further, enterprises around the globe are mopping up data at an

enormous rate. All this would, no doubt, provide excellent business opportunity for the

data storage industry. However, the requirements, being gigantic in nature, offer stiff

challenges as well and innovation holds the key to success.