Database Questions and Answers – Magnetic Disk and Flash Storage

This set of Database Multiple Choice Questions & Answers (MCQs) focuses on “Magnetic Disk and Flash Storage”.

1. In magnetic disk ________ stores information on a sector magnetically as reversals of the direction of magnetization of the magnetic material.
a) Read–write head
b) Read-assemble head
c) Head–disk assemblies
d) Disk arm
View Answer

Answer: d
Explanation: Each side of a platter of a disk has a read–write head that moves across the platter to access different tracks.

2. A __________ is the smallest unit of information that can be read from or written to the disk.
a) Track
b) Spindle
c) Sector
d) Platter
View Answer

Answer: c
Explanation: The disk surface is logically divided into tracks, which are subdivided into sectors.

3. The disk platters mounted on a spindle and the heads mounted on a disk arm are together known as ___________
a) Read-disk assemblies
b) Head–disk assemblies
c) Head-write assemblies
d) Read-read assemblies
View Answer

Answer: b
Explanation: Each side of a platter of a disk has a read–write head that moves across the platter to access different tracks.
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4. The disk controller uses ________ at each sector to ensure that the data is not corrupted on data retrieval.
a) Checksum
b) Unit drive
c) Read disk
d) Readsum
View Answer

Answer: a
Explanation: A disk controller interfaces between the computer system and the actual hardware of the disk drive.

5. _________ is the time from when a read or write request is issued to when data transfer begins.
a) Access time
b) Average seek time
c) Seek time
d) Rotational latency time
View Answer

Answer: a
Explanation: To access (that is, to read or write) data on a given sector of a disk, the arm first must move so that it is positioned over the correct track, and then must wait for the sector to appear under it as the disk rotates.
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6. The time for repositioning the arm is called the ________ and it increases with the distance that the arm must move.
a) Access time
b) Average seek time
c) Seek time
d) Rotational latency time
View Answer

Answer: c
Explanation: Typical seek times range from 2 to 30 milliseconds, depending on how far the track is from the initial arm position.

7. _________ is around one-half of the maximum seek time.
a) Access time
b) Average seek time
c) Seek time
d) Rotational latency time
View Answer

Answer: b
Explanation: Average seek times currently range between 4 and 10 milliseconds, depending on the disk model.
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8. Once the head has reached the desired track, the time spent waiting for the sector to be accessed to appear under the head is called the _______________
a) Access time
b) Average seek time
c) Seek time
d) Rotational latency time
View Answer

Answer: d
Explanation: Rotational speeds of disks today range from 5400 rotations per minute (90 rotations per second) up to 15,000 rotations per minute (250 rotations per second), or, equivalently, 4 milliseconds to 11.1 milliseconds per rotation.

9. In Flash memory, the erase operation can be performed on a number of pages, called an _______ at once, and takes about 1 to 2 milliseconds.
a) Delete block
b) Erase block
c) Flash block
d) Read block
View Answer

Answer: b
Explanation: The size of an erase block (often referred to as just “block” in flash literature) is usually significantly larger than the block size of the storage system.
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10. Hybrid disk drives are hard-disk systems that combine magnetic storage with a smaller amount of flash memory, which is used as a cache for frequently accessed data.
a) Hybrid drivers
b) Disk drivers
c) Hybrid disk drivers
d) All of the mentioned
View Answer

Answer: b
Explanation: Frequently accessed data that are rarely updated are ideal for caching in flash memory.

Sanfoundry Global Education & Learning Series – Database Management System.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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