Advanced Database Management System - Tutorials and Notes: Find the capacity of the hard disk

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## Find the capacity of a hard disk in database, How many recrods can be stored in a hard disk track? Which of the following is the correct combination of capacity of track, capacity of each surface, and capacity of disk?

#### Question:

4) Consider a disk with a sector size of 512 bytes, 14409 tracks per surface, 16947 sectors per track, 8 double-sided platters, and an average seek time of 9 ms. Which of the following is the correct combination of capacity of track, capacity of each surface, and capacity of disk (approximately)?

a) 100 MB, 200 GB, and 2 TB
b) 8 MB, 116 GB and 2 TB
c) 8 MB, 200 GB and 1 TB
d) 80 MB, 116 GB and 1 TB

b) 8 MB, 116 GB and 2 TB

Discussion:

Given,
Sector size                                                  - 512 bytes
Number of sectors per track                    – 16947
Number of tracks per surface                  14409
Number of platters                                   8 double-sided

Capacity of a track = sector size * number of sectors per track
= 512 * 16947 = 8 MB approx.
Capacity of each surface = capacity of track * number of tracks per surface
= (512*16947) * 14409 = 116 GB approx.
Capacity of the disk = capacity of each surface * number of platters * number  of pages per platter
= 116 GB * 8 * 2 = 2 TB approx.