Disk structure and access time in DBMS Theory - Mini Project: Build & Apply

Understanding Disk Structure and Access Time

📖 Scenario: You are learning how data is stored on a computer's disk and how the time to access data depends on the disk's structure.Imagine a library where books are stored on shelves arranged in sections and rows. Similarly, a disk stores data in tracks and sectors.

🎯 Goal: Build a simple representation of a disk's structure and calculate the total access time to read data from specific sectors.

📋 What You'll Learn

Create a data structure representing disk tracks and sectors with exact values

Add a configuration variable for the time to read one sector

Calculate total access time for reading multiple sectors using the disk structure

Complete the setup with a variable for the number of sectors per track

💡 Why This Matters

🌍 Real World

Understanding disk structure and access time helps in optimizing data storage and retrieval in computers and servers.

💼 Career

Knowledge of disk access times is important for database administrators, system architects, and software developers working with storage systems.

1

Create the disk structure

Create a dictionary called disk with these exact entries: 1: [10, 20, 30], 2: [40, 50, 60], 3: [70, 80, 90]. Each key is a track number and the list contains sector numbers.

DBMS Theory

# Create the disk dictionary with tracks and sectors
# Your code here

Need a hint?

Use a dictionary with track numbers as keys and lists of sector numbers as values.

2

Set the sector read time

Create a variable called sector_read_time and set it to 5 milliseconds, representing the time to read one sector.

DBMS Theory

disk = {
    1: [10, 20, 30],
    2: [40, 50, 60],
    3: [70, 80, 90]
}
# Set the sector read time in milliseconds
# Your code here

Need a hint?

Assign the number 5 to the variable sector_read_time.

3

Calculate total access time for sectors

Create a variable called total_access_time and set it to the sum of reading all sectors in track 2 multiplied by sector_read_time. Use for sector in disk[2] to iterate over sectors in track 2.

DBMS Theory

disk = {
    1: [10, 20, 30],
    2: [40, 50, 60],
    3: [70, 80, 90]
}
sector_read_time = 5
# Calculate total access time for all sectors in track 2
# Your code here

Need a hint?

Start with total_access_time = 0 and add sector_read_time for each sector in track 2.

4

Add sectors per track variable

Create a variable called sectors_per_track and set it to 3, representing the number of sectors in each track.

DBMS Theory

disk = {
    1: [10, 20, 30],
    2: [40, 50, 60],
    3: [70, 80, 90]
}
sector_read_time = 5
total_access_time = 0
for sector in disk[2]:
    total_access_time += sector_read_time
# Set the number of sectors per track
# Your code here

Need a hint?

Assign the number 3 to sectors_per_track.