And the storage capacity of a disk system having

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Unformatted text preview: urfaces, 2. Number of tracks per surface, 3. Number of sectors per track, and 4. Number of bytes per sector It is a multiple of the above four parameters. That is, Storage capacity of a disk system = Number of recording surfaces x Number of tracks per surface x Number of sectors per track x Number of bytes per sector For example, suppose a disk pack has 10 disk plates each having 2655 tracks. Suppose there are 125 sectors per track, and each sector can store 512 bytes. Since the disk pack has 10 disk plates, so it will have 18 recording surfaces (excluding the upper surface of the topmost disk and the lower surface of the bottommost disk). Hence the capacity of this disk pack will be = 18 x 2655 x 125 x 512 = 3,05,85,60,000 bytes = 3 x 10 9 bytes (approximately) = 3 GB (3 Giga Bytes). Essentially one character can be stored per byte. So a disk system with 3 GB capacity can store 3 billion characters of information. Notice that the more recording surfaces a particular disk system has, the greater its storage capacity will be. For example, in case of a disk system having only one disk (i.e., a floppy disk), the storage capacity of a double-sided disk plate will be about twice that of a single-sided one. And the storage capacity of a disk system having multiple disk plates (i.e., a disk pack) will be many times more than a single-disk system. As the storage capacity of a disk system is also directly proportional to the number of tracks per surface, disks having larger diameter can have more tracks and larger storage capacity. However, disk size cannot be made too large because it will affect the overall size of the disk unit. And the constant effort of the designers of disk systems is to provide more storage capacity in as compact form as possible. Hence instead of increasing the disk size for larger storage capacity, the designers prefer to increase the storage capacity by increasing th& tracks per inch of surface and bits per inch of track. That is, a constant goal of the designer...
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This document was uploaded on 04/07/2014.

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