Professional Courses
Industry-relevant training in Business, Technology, and Design to help professionals and graduates upskill for real-world careers.
Categories
Interactive Games
Fun, engaging games to boost memory, math fluency, typing speed, and English skills—perfect for learners of all ages.
Typing
Memory
Math
English Adventures
Knowledge
Enroll to start learning
You’ve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Introduction to Multiple Platter Mechanism
Unlock Audio Lesson
Today, we're going to talk about the multiple platter mechanism in disk drives. Can anyone tell me what they understand by this term?
Does it mean that the disk has more than one platter to store data?
Exactly! Multiple platters allow for more efficient data storage. Each platter has two sides for reading and writing data. What do you think is the benefit of having multiple platters?
It sounds like we can save space and possibly increase the amount of data we can store.
Correct! More platters mean more surfaces to record data. Now, let’s remember that each platter rotates at a constant angular velocity. This is vital for maintaining consistent access times across tracks. Here’s a mnemonic: 'VARY' - 'Velocity Always Remains the same, Yonder routes data travel.' Let’s move to how data is accessed using these platters.
Addressing in Disk Drives
Unlock Audio Lesson
When we access data, we need to locate where that data is stored. This brings us to the addressing format. Can someone tell me how data is addressed in disks?
Isn't it done by using track numbers and sector numbers?
Yes! We identify data using the track number, sector number, and surface number. This means if we know these three identifiers, we can find our data quickly. What do you think happens if we have lots of sectors on a single track?
It could make finding specific data slower if the addressing isn't efficient!
Good point! Efficient addressing helps prevent delays. For memory, think 'SSS' - 'Sector, Surface, Track' for locating data efficiently. Let’s explore density in these tracks and how it affects storage.
Bit Density and Zoning
Unlock Audio Lesson
Now let’s dive into bit density. Can anyone explain why inner tracks might have a different bit density compared to outer tracks?
I remember reading that outer tracks have to store more data due to having more space.
Exactly right! Outer tracks have more physical space, yet the bit density is typically less. Hence, we introduce zoning, where tracks are split into zones to maintain density. What might be a downside of this zoning?
I think it could make the circuit design more complex?
Yes! This complex control circuitry is a trade-off between higher density and increased system complexity. Remember, 'DICE' for Density Increases Complexity Everywhere! Now, let's wrap up with how these mechanisms interplay.
Fixed vs. Movable Heads
Unlock Audio Lesson
We have different types of head mechanisms: fixed and movable. What do you think the main difference is?
Fixed heads use one head per track, right?
Correct! Each track has its own head in fixed mechanisms. In movable heads, a single head moves across tracks. What could be a benefit of a fixed head?
It might be faster since it doesn't have to move around.
Exactly! However, movable heads offer flexibility and can be more space-efficient. Keep in mind the keyword 'FLEX' – Fast vs. LEss EXpensive. Let’s summarize what we’ve learned today.
Conclusion and Summary
Unlock Audio Lesson
In conclusion, the multiple platter mechanism allows for efficient data storage and retrieval. Can anyone summarize some key points we've discussed?
We learned about addressing formats, fixing versus movable heads, and how bit density works with zoning.
Well said! Always keep in mind the complexity of control circuits and the constant angular velocity of disks. For review, just remember 'DICE' and 'SSS'. Great work today, everyone!
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
The multiple platter mechanism allows for efficient data storage and retrieval on disk drives by utilizing fixed or movable heads to read/write data across concentric tracks. It covers concepts such as track addressability, bit density in different zones, problems related to space wastage, and the complexities of the control circuitry involved in managing these dynamics.
Detailed
Detailed Summary
The section delves into the operation of hard disk drives using the multiple platter mechanism, where disks rotate at a constant angular velocity to retrieve information efficiently. The concept of individual tracks and sectors being addressable allows the system to minimize the time required for data access, regardless of the data's physical location (inner or outer track).
Key features include:
- Addressing Format: Each sector is identified by a combination of track number, sector number, and surface number, aiding in quick data retrieval.
- Bit Density: Inner tracks typically have higher bit density compared to outer tracks, which presents a challenge in terms of data storage efficiency. The section discusses the zoning concept where tracks are divided into zones to maintain consistent bit density while allowing increased data storage on outer tracks.
- Head Mechanisms: The roles of fixed and movable heads are explored, highlighting how fixed heads dedicate one read/write head per track, while movable heads use a single head to access multiple tracks.
- System Complexity: The complexity of the control circuitry in managing multi-platter drives and dynamic bit density across the tracks is addressed, indicating trade-offs between simplification and efficiency.
Overall, this section articulates the fundamental principles behind the operation of disk drives, focusing on the intricacies and design considerations inherent in the multiple platter mechanism.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Constant Angular Velocity of Disks
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Secondly, disk rotates in a constant angular velocity. Now you just see since it is rotating a constant angular velocity, so the time required to cover this particular length will be equal to the time required to traverse this particular length. Because it is rotating in a constant angular velocity, the angular velocity is the same. So, this cone will be traversed in a constant time so that means, this information will be retrieved in lesser time...
Detailed Explanation
Disks in a storage device rotate at a constant angular velocity, meaning the speed at which the disk turns does not change. This consistency allows for uniform time to retrieve information from different parts of the disk, regardless of whether the data is located on an inner or outer track. Consequently, the time taken to locate and retrieve data is efficient, leading to faster data access.
Examples & Analogies
Think of a merry-go-round at a playground. When it spins at a steady speed, anyone trying to grab a toy placed on it can do so in the same amount of time, regardless of where they stand. If it spins faster or unpredictably, reaching for toys (data) would take more time and effort.
Tracks, Sectors, and Spatial Efficiency
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Individual tracks and sectors are addressable. This is an important point. If you know the track number and the sector number, you can access specific data directly. However, this precise targeting can lead to inefficiencies if too much space is wasted on the outer tracks, where density is less. To reduce this waste, concepts like zoning come into play...
Detailed Explanation
Data on a disk is stored in tracks and sectors, which can be thought of as concentric circles (tracks) segmented into slices (sectors). Knowing the track and sector numbers allows a read/write head to access data directly. However, outer tracks often contain less data because they have lower bit density, making them less efficient. The zoning method provides a solution by grouping tracks into zones with consistent bit density, allowing for more effective storage across the disk.
Examples & Analogies
Imagine a bookshelf with shelves (tracks) and books (sectors) arranged in a specific order. If the top shelf has thicker books (more data) than the bottom shelf, the bottom shelf will look less efficient. If you reorganize the books so that each shelf has the same thickness, you make better use of the shelf space.
Fixed vs. Movable Read/Write Heads
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Now say I am having concentrated track; now I have to read information from those particular track. In case of fixed head, we have a separate head for each and every track. In contrast, a movable head moves outward and inward to access different tracks...
Detailed Explanation
There are two types of read/write head mechanisms in disk storage: fixed heads, where each track has its own dedicated head, and movable heads, where one head moves to access different tracks. Fixed heads can enable faster access since there's no movement required, but they are less flexible. Movable heads save space and can handle more tracks with fewer heads. However, they take slightly longer to access data because of the movement required to switch tracks.
Examples & Analogies
Think of a library. A fixed-head system is like having a librarian standing at each bookshelf ready to grab a book; they're always ready but require more staff. A movable head is like having one librarian who runs to where the book is needed, which takes time but requires fewer librarians to cover all areas.
Removable vs. Fixed Disks
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
In case of removable disks, we have a disk drive; we can put one disk, do work with that disk, and remove it to place another one. In fixed disks, the disk is permanently mounted...
Detailed Explanation
Removable disks allow users to insert and remove storage media like CDs or floppy disks whenever needed. This offers flexibility but can limit some performance aspects. On the other hand, fixed disks are integrated into devices, providing consistent access without the need to swap media, often leading to faster data access rates.
Examples & Analogies
Consider a DVD player where you can swap DVDs (removable disks) versus a digital library app that has all your movies stored in one place (fixed disks). Swapping DVDs gives you variety, while the app gives you quick access without delays.
Understanding Cylinders and Sectors
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Now when we talk about tracks, there is a concept of the cylinder. If we consider a specific track across all surfaces, that forms a cylinder. Like this, all tracks on a particular disk surface aligned vertically create a cylindrical shape.
Detailed Explanation
The cylinder concept is crucial in understanding how data is organized on multiple disks. When you think of a track as a circle on each disk surface, stacking all tracks across disk surfaces vertically forms a cylinder. This allows for efficient access since all data from that cylinder can be accessed by moving the read/write head directly to the correct vertical position without moving laterally.
Examples & Analogies
Picture a multi-layered cake with each layer representing a track on a different disk surface. When you want a slice from a specific tier (track), you can reach directly down vertically through all layers instead of moving across them horizontally, much like how a read/write head accesses data within the same cylinder.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Multiple Platters: Allows for higher data storage by utilizing both sides of disks.
-
Constant Angular Velocity: Disks must rotate consistently to maintain data retrieval speed.
-
Address Structure: Data is accessed via track number, sector number, and surface number addresses.
-
Bit Density: Varies based on the position on the platter, with outer tracks typically having lower density.
-
Zoning Concept: Helps optimize data storage and access time by organizing tracks into zones.
-
Head Techniques: Fixed heads use one head per track, while movable heads share one head across tracks.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
An HDD with three platters has a total of six surfaces, allowing for more efficient data access than single platter drives.
-
In a zoned arrangement, the outer tracks (while wider) store less data per unit area compared to inner tracks which are densely packed.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
-
Platter after platter, the data will flow, / With constant speed, the disks will glow.
📖 Fascinating Stories
-
Imagine a library where each book (data) is marked with codes (addresses). In this library, each section (track), shelf (surface), and book (sector) has a place, making it easy to find what you need!
🧠 Other Memory Gems
-
Remember 'SST' - Surface, Sector, Track - for finding data on a disk!
🎯 Super Acronyms
DICE
- Density Increases Complexity Everywhere
- reminding us of the trade-offs in disk design.
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Platter
Definition:
A flat, usually circular disk on which data is stored in a hard disk.
-
Term: Bit Density
Definition:
The amount of data stored per unit area on a disk.
-
Term: Zoning
Definition:
A method of organizing tracks into various zones, affecting how much data can be stored.
-
Term: Track
Definition:
A circular path on the disk surface where data is recorded.
-
Term: Sector
Definition:
A segment on the track used for data storage that represents a fixed number of bytes.
-
Term: Seek Time
Definition:
The time it takes for the read/write head to move to the correct track.
-
Term: Rotational Latency
Definition:
The time it takes for the desired sector to rotate under the read/write head.