Discuss the mechanism to read data from and write to a disk, Database Management System

Assignment Help:

Discuss the mechanism to read data from and write to a disk?

Disk read/write heads are mechanisms in which read data from or write data to disk drives. The heads have gone by a number of changes over the years.

In a hard drive, the heads 'fly' above the disk surface along with clearance of as little as 3 nanometres. The "flying height" is constantly decreasing to enable higher field density.

The flying height of the head is controlled through the design of an air-bearing etched onto the disk-facing surface of the slider. The role of the air bearing is to manage the flying height constant as the head moves over the surface of the disk. If the head hits the disk's surface, a catastrophic head crash can result.

The heads themselves begin out same to the heads in tape recorders-easy devices made out of a tiny C-shaped piece of highly magnetizable material known as ferrite wrapped in a fine wire coil. While writing, the coil is energized, a strong magnetic field forms within the gap of the C, and the recording surface adjacent to the gap is magnetized.

While reading, the magnetized material rotates past the heads, the ferrite core concentrates the field, and a current is produced in the coil. The gap where the field is extremely strong is quite narrow. That gap is roughly equal to the thickness of the magnetic media on the recording surface. The gap denotes the minimum size of a recorded field on the disk. Ferrite heads are large, and write fairly large characteristics.


Related Discussions:- Discuss the mechanism to read data from and write to a disk

Types of locks, Types of Locks There are two necessary types of locks: ...

Types of Locks There are two necessary types of locks: Binary lock : This locking mechanism has two states for to a data item: locked or unlocked Multiple-mode loc

What is the purpose of storage manager, What is the purpose of storage mana...

What is the purpose of storage manager? The storage manager is responsible for the following a) Interaction with the file manager b) Translation of DML commands in to low

Develop a simple database of student records, In this programming assignmen...

In this programming assignment, you will develop a simple database of student records. Here are the requirements: 1) A student record contains a name and a number. We assume tha

Modify - referential integrity, Update or Modify operation alters the exist...

Update or Modify operation alters the existing values. If these operations alter the value that is the foreign key also, the only check need is the similar as that of the Insert op

Higher normal forms, Higher Normal Forms Is there more normal forms beyond...

Higher Normal Forms Is there more normal forms beyond BCNF? Yes, though, these normal forms are not based on the concept of functional dependence. More normalisation is needed if

Primary and foreign key, Primary Key The primary key is the candidate k...

Primary Key The primary key is the candidate key that is selected by the database designer as the principal denotes of identifying entities within an entity set. The left candi

Create a entity-relationship diagrams, This project requires you to create ...

This project requires you to create a database design.  Your design will be documented in a set of Entity-Relationship diagrams.  Draw a set of Entity-Relationship diagrams to mode

What is dml, What is DML (Data Manipulation Language)? This language th...

What is DML (Data Manipulation Language)? This language that enable user to access or manipulate data as organised by appropriate data model. Procedural DML or Low level: DM

Define the normalisation form, Define in which normalisation form if an att...

Define in which normalisation form if an attribute of a composite key is dependent on an attribute of other composite key. Ans: 3NF A relation is in 3 NF if an attribute of

Difference among a primary index and a secondary index, What is the differe...

What is the difference among a primary index and a secondary index? Primary Index: A primary index is an ordered file whose records are of fixed length along with two fields.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd