• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
Chapter 4 1
 

Chapter 4 1

on

  • 559 views

 

Statistics

Views

Total Views
559
Views on SlideShare
559
Embed Views
0

Actions

Likes
0
Downloads
3
Comments
1

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel

11 of 1 previous next

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Chapter 4 1 Chapter 4 1 Presentation Transcript

    • Create a directory tree
      See page 108, 109, 110
    • Operations of Adding a New File
      Store Properties
      Locate a free inodeas 47
      Record the file information in the inode
      Store Data
      Locate disk blocks for file content such as 627, 200, and 992.
      Record Allocation
      Record the sequence of block numbers in the disk allocation section of the inode
      Add Filename to Directory
      Add the new entry (47, userlist) to the directory.
    • Looking inside a directory
      Directory is a special kind of file that contains a list of names of files.
      Ls – 1ia demodir //i for inode number
      Ls –ia / //root and parent of root //point to itself
    • The file system in practice
      What will happen when you type:
      > cat userlist
      The kernel searches the directory for the filename: userlist, inode number 47 found
      Locate the real inode 47 in inode table. The inode contains a list of data block numbers.
      Go to the data block one by one to read the data with read system call.
      The permission is also checked from inode
    • STRUCTURE OF A REGULAR FILE
      The blocks marked "direct”
      contain the numbers of disk blocks that contain real data.
      The block marked "single indirect"
      refers to a block that contains a list of direct block numbers.
      To access the data via the indirect block, the kernel must read the indirect block, find the appropriate direct block entry, and then read the direct block to find the data.
    • STRUCTURE OF A REGULAR FILE
      The block marked "double indirect" contains a list of indirect block numbers, and
      the block marked "triple indirect" contains a list of "double indirect " block numbers refers to a block that contains a list of direct block numbers.
      Assume
      that a logical block = I K bytes
      A block number is addressable by a 32 bit (4 byte) integer.
      Then a block can hold up to 256 block numbers.
    • A single indirect data block can hold 256 block numbers (1024 bytes/4 bytes)