Skip to main content

Disk Management in O/S

 DISK FORMATTING :-

  It is the configuring process of a data storage media sich as a hard drive, floppy disk or flash drive for initial use. Any existing file on the drive would be erased with disk formatting. Disk formatting os usually done before initial installation or before installation of a new O/S. It is also done if there is need of additional storage in the computer.
 
  A new magnatic disk is a blank state, it just a platter of magnatic recording material. Before a disk can store data, it must be divided into sectors that the disk controllr can read and write. This process is called low-level formatting or physical formatting. Low level formatting fills the disk with a special data structure for each sector . The data structure for each sector typically consistes of "a header, a data area and a trailer".

Header and trailer :-
  Header and trailercontain information used by disk controller, such as a sector number and error-correcting code (ECC).

Data area :-
  Most hard disks are low level formatted at the factory as a part of manufacturing process. For many hard disks,  when thye disk controller is instructed to low-level formate the disk, it can also be told how many bytes of data space to leave between all sectors. It is usually possible to choose among a few sizes, such as 256,512,1024 bytes.

Formatting a disk with a large sector size means that fewer sector can fit on each track, but it alo means that fewer header and trailers are written on each track and more space is available for user area. Some O/S can handle only a sector size of 512 bytes.

Before it can use a disk to hold files, the operating system still neds to record its own data structure on the disk. It does in two steps :-
 
i > Partition :- The first step is to partition the disk into one or more cylinders. The operating system can treat each partition as though it were a seperate disk. For instance, one partition can hold a copy of operating system executable code while another holds user files.

ii > Logical formatting :- The second step is logical formattung or creation of a file system. Data strusture omto the disk. These data structures may include maps of free and allocater space and an initial empty directory.


Cluster :-
   To increase efficiency, most file system group blocks together into large chumks, called clusters. Disk Input-output is done via blocks but file system Input-output is done by a cluster.

Raw disk :- 
    Some operating system give special programs, the ability to use a disk partition as a large block. The arary is of logical block. The array is sometimes called raw disk.
Share, Follow and please comment if you find anything incorrect or to share more information about the topic discussed above





Labels:

Comments

Post a Comment

Please comment.

Popular posts from this blog

Process Scheduling And Types of Process Schedular :-

        ⇰ PROCESS SCHEDULING Process Scheduling  is a task  of Operating System that schedules processes of different states like new, ready, waiting, terminated  and running.This scheduling helps in allocation of CPU time for each process, and Operating System allocates the CPU time for each procss. And the process scheduling plays important role to keep the CPU busy all the time.  ⏩   Followings are some objectives of Process Scheduling :-  i > To increase the amount of users within acceptable response times.  ii > To maintain the balance between response and utilization of system. iii > To decrease the enforce priorities and  give reference to the processes holding the key resources.      ⇰  PROCESS SCHEDULAR A scheduler carries out the pro cess scheduling work. Schedulers are often implemented so they keep all computer resources busy and  allows multiple users to share system resources  to achieve  multiprogramming .  There are  mainy three types of pro
8 comments
Read more

Process & Its state And process control block :-

                ⇰  PROCESS :- A process can be thought of as a program in execution. Means when any program is executed it becomes process. A processwill need certain resources such as CPU time , memory, files and I/O devices to complete its task. These resources are allocated to the process either when it is created or at the time of execution.             A process is the unit of work in most systems. A system consistes of a collection of processes. All these processes may execute concurrently. Traditionally a process contained only a single thread. Most modern operating ststems now supports processes that have multiple threads.         The operating system is responsible for several important works of process management as - the creation and deletion of process, the schrduling of process, communication and deadlock handling of process. Process is broudly divided into two types:-  i> System  Process. ii> User Process. Early computers allowed only one program be ex
Post a Comment
Read more

Semaphores In Process Synchronization

   ⇰  Semaphores :-   Semaphore is actually a method or tool to prevent race condition. Race condition can cause loss of data or even deadlock situation. For prevention from these conditions, the semaphore is one of the method.  Semaphore was proposed by Dijkstra in 1965. Simaphore    is a very significant technique to manage concurrent processes.  Semaphore is useful tool in the prevention of race condition. But the use of semaphore never means a guarantee that a program is free from these problems.     Semaphore is an integer variable which is used in mutual exclusive manner by various concurrent cooperative processes in order to acheive synchronization. Hence semaphore is one of the way to achieve synchronization.  Semaphore is basically  a variable which is non-negative and shared between threads. This variable is used to solve the critical section problem and to achieve process synchronization in the multiprocessing environment. Semaphore contains some operations as f
Post a Comment
Read more