Suppose that a disk unit has the following parameters: seek time \(s=20\) msec;
rota tional delay \(r d=10 \mathrm{msec} ;\) block transfer time \(b t t=1
\mathrm{msec} ;\) block size \(B=2400\) bytes; interblock gap size \(G=600\) bytes.
An EMPLOYEE file has the following fields:
\(\mathrm{SSN}, 9\) bytes; LASTNAME, 20 bytes; fIRSTNAYE, 20 bytes; MIDOLE
INIT\(, 1\) byte; BIRTHOATE, 10 bytes; ADDRESS, 35 bytes; PHONE, 12 bytes;
SUPERVISORSSN, 9 bytes; DEPARTMENT, 4 bytes; JOBCODE, 4 bytes; deletion
marker, 1 byte. The EMPLOYEE file has \(r=30,000\) records, fixed-length format,
and unspanned blocking. Write appropriate formulas and cal. culate the
following values for the above eMPLoyee file:
a. The record size \(R\) (including the deletion marker), the blocking factor \(b
f r,\) and the number of disk blocks \(b\)
b. Calculate the wasted space in each disk block because of the unspanned orga
nization.
c. Calculate the transfer rate \(t r\) and the bulk transfer rate brr for this
disk unit (see Appendix B for definitions of tr and btr).
d. Calculate the average number of block accesses needed to search for an
arbitrary record in the file, using linear search.
e. Calculate in msec the average time needed to search for an arbitrary record
in the file, using linear search, if the file blocks are stored on consecutive
disk blocks and double buffering is used.
f. Calculate in msec the average time needed to search for an arbitrary record
in the file, using linear search, if the file blocks are not stored on
consecutive disk blocks.
g. Assume that the records are ordered via some key field. Calculate the
average number of block accesses and the average time needed to search for an
arbitrary record in the file, using binary search.
