The Solaris Operating Environment ufs File System Chap' 7

1
The Solaris Operating Environment ufs File
System(Chap. 7)

• ICE System Consultant 2nd
• 2002? 6? 7?

2
Objectives

• Describe the 3 different types of file systems in
  the Solaris Operating Environment
• Define the term file system
• List the components that are contained in the
  structure of a file system
• Create a new ufs file system using the newfs
  command

3
File System Types

• Disk-based file systems
• General file system
• Distributed file systems
• NFS, DFS
• Pseudo file systems
• Virtual file system (memory base)

4
Disk-based File System

• Hard disks, CD-ROMs, diskettes, and DVDs
• Ufs
• Standard UNIX file system
• Hsfs
• The high sierra file system
• Used in CD-ROM media
• Pcfs
• UNIX implementation of the DOS file attribute
  table(FAT32)
• Udfs
• The universal disk format file system for optical
  storage targteed at DVD and CD-ROM media

5
Distributed File Systems

• NFS
• Network file system
• Allows users to share files between networks

6
Pseudo File System

• Memory-based file system
• Tmpfs
• The temporary file system
• Used for file storage in memory (/tmp)
• Destroyed every time the system is reboot
• Swapfs
• Used by kernel to manage swap space on disks
• Fdfs
• The file descriptor file system
• Opening files using file descriptor (/dev/fd)
• Procfs
• For active processes (/proc)

7
Introducing the Solaris Operating Environment ufs
File System

• To a user
• Collection of files and directories
• To OS
• Collection of control structures and data blocks
• Solaris ufs File Systems Residing on Disk Slices

8
Basic Disk Structures

• Disk label (VTOC)
• Contains the partition table for disk
• Located in the first disk sector (512-byte
  blocks)
• Boot block
• 1 15 sector
• Only the root file system has an active boot
  block
• Superblock
• The file system is described by its superblock
• Table of information about the file system
• Number of data blocks
• Number of cylinder groups
• name of the mount point
• File system state flag

9
Basic Disk Structures (Cont.)

• Backup superblock
• Backup for superblock (why?)
• Cylinder groups
• By dividing the partition into cylinder groups,
  disk access is improved
• Cylinder group blocks
• Number of inodes
• number of directories
• Free blocks, free inodes, and free fragments
• Free block map
• Used inode map

10
Basic Disk Structures (Cont.)

• Inode table
• Index node
• Contains the inodes for the cylinder group
• Data blocks
• Unit of storage for data
• Default size is 8Kbyte

first cylinder group
ufs filesystem
second cylinder group
ufs file system structure
11
Basic Disk Structures (Cont.)

• Inode
• Contains
• Type of file and the access modes (permission)
• UID, GID
• Size of the file
• Time that last accessed or modified and inode
  changed
• Total number of data blocks used by
• Direct pointer and indirect pointer
• Direct pointer
• 12 pointers which refer directly to data blocks
• 12 8K 96K

12
Basic Disk Structures (Cont.)

• indirect pointer
• 3 types
• Single indirect pointer
• 8K 2048 16M
• Double indirect pointer
• 16M 2048 32G
• Triple indirect pointer
• 32G 2048 70T
• Ideally ufs can make 70Tbyte data, but can make
  about 1Tbyte file

13
Basic Disk Structures (Cont.)

• Data blocks
• 8Kbyte logical block size and further divided
  into a 1Kbyte fragment
• For example, following figure represent the
  situation that 2 files are in same block
• If the size of file1 has grown, the ufs assign
  new data block to file1

14
Creating ufs File Systems

• On a newly partitioned disk, must created file
  system
• newfs is c\format command in DOS environment
• Example
• newfs /dev/rdsk/ctds
• Caution!!
• Carefully identify the question in processing the
  newfs command
• You may destroy the whole system