1. Given: a block addressible disk drive with 4,200 bytes per track and overhead

ID: 402305 • Letter: 1

Question

1. Given: a block addressible disk drive with 4,200 bytes per track and overhead 50

bytes per block. A le contains 50 byte records. How many records can be stored

per track if the blocking factor is 20? Please show all your work!

2. Consider a le with 3200 records occupying two hundred data pages (i.e., B=200

and R=16). The average time to read or write a disk page is 15 microseconds (I.e.,

D=15 microseconds), and the average time to process a record is 0.1 microseconds

(i.e., C=0.1 microseconds). The time required to apply the hash function is 0.5

microseconds (i.e., h=0.5 microseconds). Assume (1) only scan and equality search

operations are used, and (2) on average, the scan operation is used in 10% of the

cases and the remaining cases use equality searches. Which le organization (heap,

sorted, or hashed) would you select and why?

size of dats subblocks = 50 * 20 = 1000

overhead per block = 50

number of blocks = 4200/(1000 + 50) = 4

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