6. External Memory
True or False:
1. T/F – The underlying substrate in the magnetic disc is non-magnetic.
ANS: T
2. T/F – Bits of data are written and read using a magnetic coil.
ANS: F
3. T/F – Electric patterns that pass through the coil decides whether the bit is positive or
negative.
ANS: T
4. T/F – The size of the head is equal to the gap size between tracks to help read/write.
ANS: F
5. T/F – The time it takes to read the tracks closer to the center of the disk is lesser than
the tracks near the circumference.
ANS: T
6. T/F – Multiple zone layout helps in maintaining constant access speed for all sectors in
the track.
ANS: F
7. T/F – Disks can be magnetized on both sides to increase the number of bits that can
be stored.
ANS: T
8. T/F – Rotational positional sensing is used to enable better control over the read/write
ports.
ANS: F
9. T/F – RAID is a set of virtual disk drives that the operating system sees as one single
disk.
ANS: F
10. T/F – RAID enables simultaneous access of data from different drives.
ANS: T
11. T/F – Like magnetic disks, CDs can also be made to store data on both sides.
ANS: F
12. T/F – The tape drive is a direct access memory type.
ANS: F
13. T/F – Phase change disks are a form of magnetic disks.
ANS: T
14. T/F – The principle disadvantage of RAID level 1 is its cost.
ANS: T
15. T/F – The set of all sectors relative to a platter is termed as a cylinder.
ANS: F
16. T/F – Except floppy disks, other disks can rotate at a minimum speed of 3600 rpm.
ANS: T
Multiple Choice Questions:
1. Redundancy is a built-in feature here
A. Magnetic disks
B. RAID
C. Serial I/O tapes
D. Optical disks
ANS: B
2. The megnetoresistive sensor (MR) increases what capability in newer rigid disks?
A. Operating frequency
B. Area
C. Access times
D. None of the above
ANS: A
3. Each sector in the disk can be reached at the same time using this layout
A. Multiple zone layout
B. Constant velocity layout
C. Static sector layout
D. None of the above
ANS: B
4. Data access time depends on
A. Seek time
B. Operating frequency
C. Rotational delay
D. All of the above
ANS: D
5. In RAID architecture, data is distributed as an array by a scheme called
A. Interleaving
B. Stripping
C. De-centralizing
C. None of the above
ANS: B
6. RAID level 0 is primarily used in applications where
A. Cost is a priority
B. Reliability is a priority
C. Area is a priority
C. All of the above
ANS: A
7. The chief difference between RAID 4 and RAID 5 lie with
A. Parity strips
B. Redundant disks
C. Performance
D. All of the above
ANS: A
8. Typical technique used to write/read data onto magnetic tapes is
A. Compound parallel recording B. Serpentine recording
C. Multiple access recording
D. None of the above
ANS: B
9. Bit density is more in which device
A. Compact disk
B. Magnetic tape
C. DVD
D. Magnetic disk
ANS: C
10. Change of phase in phased disks is performed by
A. Optical light
B. Laser
C. Magnetization
D. None of the above
ANS: B
11. The primary advantage of RAID level 6 is
A. High data availability B. High data accessibility
C. Low data loss
D. All the above
ANS: A
12. Data in CDROM are arranged in blocks with what of the following fields?
A. Data
B. Auxiliary
C. Header
D. All the above
ANS: D
13. What property of the CDROM is similar to magnetic disks
A. Constant linear velocity
B. Access rate
C. Parallel access frequency
D. None of the above
ANS: A
14. What property makes the CDROM be used for archival storage.
A. Redundancy
B. Rewritable
C. Removable
D. All the above
ANS: C
15. Which of the following is not a head mechanism
A. Aerodynamic gap
B. Intrasector gap
C. Fixed gap
D. Contact
ANS: B
16. Which of the following substrates for magnetic disks has better capacity to withstand
shock and damage
A. Resin
B. Poly-crystalline
C. Glass
D. Quartz
ANS: C
Fill up the blanks:
1. For a read or a write the ____________ rotates beneath the head.
ANS: Platter
2. ____________ are used between tracks to minimize errors and misalignments.
ANS: Gaps
3. The ____________ disk has an aerodynamic head for read-write operation.
ANS: Winchester
4. ____________ is defined as the number of bits per linear inch.
ANS: Linear Density
5. __________ is the time required to move data between different regions of the disk
and it depends on __________.
ANS: Transfer time, disk rotation speed
6. There are _________ types of RAID levels/types.
ANS: Seven
7. _____________ uses parity check while ____________ uses error correcting codes to
ensure reliability.
ANS: RAID 3, RAID 4
8. Blocks on magnetic tapes are separated by ___________.
ANS: Intra-record gaps
9. ___________ devices have high amounts of storage capacity.
ANS: High definition optical disks
10. Recovery from failure in _________ is not very difficult.
ANS: RAID 1
11. ________ suffers in a RAID level 3 architecture in a transaction-oriented environment.
ANS: Performance
12. A _________ has one read-write head per track.
ANS: Fixed-head disk
13. A set if consecutive strips that map to exactly one array is called a ___________.
ANS: Stripe
14. ___________ and ____________ are form of error checking/correcting mechanisms.
ANS: Parity check, Error correcting check
15. __________ architecture approximately doubles the amount of disks used.
ANS: RAID 1
16. ___________ uses bit-interleaved parity for error checking.
ANS: RAID 3