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INODE,METADATA,SUPERBLOCK




INODE
A data structure that stores the below information about a file
----------------------------------
  • Size of file
  • Device ID
  • User ID of the file
  • Group ID of the file
  • The file mode information and access privileges for owner, group and others
  • File protection flags
  • The timestamps for file creation, modification etc
  • link counter to determine the number of hard links
  • Pointers to the blocks storing file’s contents
------------------------------------------------
Inode doesnot store the file name and it is stored seperately, greatest advantage is hardlink can be created for different file name sharing same inode.

Meta data
===========


Its data about a data. Suppose you own a vehicle there are registration and other details of the vehicle that is not the part of it. Metadata gives info like

  • File name
  • Owner
  • Creation date
Location on storage medium


SUPER BLOCK
============



Metadata describes the structure of the file system. Most common metadata structure are superblock, inode and directories.

  • File system type
  • Size
  • Status
  • Information about other metadata structures
  • Free inodes and blocks

 dumpe2fs /dev/hda3 | grep -i superblock


Primary superblock at 0, Group descriptors at 1-1
Backup superblock at 32768, Group descriptors at 32769-32769
Backup superblock at 98304, Group descriptors at 98305-98305
Backup superblock at 163840, Group descriptors at 163841-163841
Backup superblock at 229376, Group descriptors at 229377-229377
Backup superblock at 294912, Group descriptors at 294913-294913
If superblock is corrupted, execute fsck in backup super block

Example



e2fsck -b 32768 /dev/hda1



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