Week 5 - Data Storage

Question 1

Do hard disks normally store data magnetically or electronically?

Answer 1

Magnetically.

Question 2

How is information stored on hard disks? Hint: Not magnetically or Electronically.

Answer 2

Information on a hard disk is stored on platters. The information on these platters is accessed by a read-write head.

Question 3

What is an Actuator in terms of hard disks?

Answer 3

An Actuator is what moves the read-write head to different locations on the platter.

Question 4

What is an Platter in terms of hard disks?

Answer 4

What the data is stored on.

Platters can be double sides to store more data.

Question 5

TRUE OR FALSE: You can only have one platter in a hard disk.

Answer 5

FALSE. You can have more than one.

Question 6

What is the Read-Write head in terms of hard disks?

Answer 6

The pointer that points to the location of the data to be accessed. It is physical and hovers above the platter at that location.

Question 7

What are the three parts to a platter structure? These are what platters are organised into.

Answer 7

Track
Sector
Cluster
Geometric Sector

Question 8

What is a Track in a Platter?

Answer 8

A circular section that goes around the platter.

Question 9

What shape is a Platter?

Answer 9

A circle, with a hole in the middle.

Question 10

What is a Sector in a Platter?

Answer 10

A segment of a track.

Question 11

What is a Cluster in a Platter?

Answer 11

A sequence of adjoining sectors on the same track. They join on their short sides.

Question 12

What is a geometric sector in a Platter?

Answer 12

A number of sectors on different tracks, joining vertically reaching from the certain of the platter out to the each. Looks like a slice of pie (Platter is a circle).

Question 13

How much data does a sector normally contain?

Answer 13

Just over 512 bytes.

512 of it for the storage, and some more data to store header data etc..

Question 14

What is stored in a sector?

Answer 14

The actual data
Header
Synchronisation Area
Cyclic Reducancy Checker value (CRC)

Question 15

What is the Synchronisation area?

Answer 15

An area used internally by the disk to guide the read process in that sector.

Question 16

What is the Header area?

Answer 16

An area that stores data on the sector number, location and status info.

Question 17

What is the Cyclic Redundacy Checker Value (CRC)?

Answer 17

Data used to ensure the integrity of the data in the sector.

Question 18

What secotrs are the most used/visited?

Answer 18

The outer rings of sectors.

Question 19

Why are Clusters used as storage sets?

Answer 19

Because sectors themselves are often too small to store all the data in a file. Thus, sectors are grouped into clusters.

Question 20

What is a Cylinder in terms of hard disks?

Answer 20

Multiple platters stacked on top of each other.

Question 21

What is Logical Block Addressing (LBA)?

Answer 21

A way of numbering sectors in multiple platters. IT uses a linear index scheme: first block is LBA 0, the second is LBA 1 etc..
LBA acts as a physical address to these locations on the platters.

Question 22

How many bits are used for addressing in LBA?

Answer 22

48 bits.

Question 23

Where is the Master Boot Record stored?

Answer 23

In the first sector of the main hard disk: LBA 0.

Question 24

What does the Mater Boot Record do?

Answer 24

It allows for the system to actually boot and startup. IT also stores data on partition tables for disks.