CAS CS 460: Introduction to Database Systems

Problem 1. (20 points)
Consider a hard disk drive that has 5 double-sided platters, each surface has 1000 tracks, each
track has 256 sectors of size 1024 bytes. Each block (disk page) comprises of 8 sectors. The seek
time between adjacent tracks in 1ms and the average seek time between two random tracks is
25ms. The disk rotates at a speed of 7200 rpm (revolutions per minute).
Assume that we have a file of size 1 MB and it contains 2048 equal-sized records.
1. What is the size of a block? How many records fit in a block? How many blocks are required
to store the entire file?
2. What is the capacity of each cylinder? How many records can be stored on the disk (total)?
3. If the file is stored “sequentially”, how long will it take to read the whole file? Assume that
for sequential writes data are written in adjacent cylinders (or tracks) once a cylinder (track)
is full.
4. If the blocks in the file are spread “randomly” across the disk, how long will it take to read
the whole file?

DETAILED ASSIGNMENT

20210331160631460_hw_3