Question

Please answer the following questions because I am not understanding it

Description Investigate UNIX/Linux Files Systems by answering the questions below

Requirements

 Save the recorded information in an ASCII file named “prog2.txt”. The file, “prog2.txt”, must be located in the directory: $HOME/itec400/homework

 Make sure the permissions on “prog2.txt” are set to 705.

 Solutions to problems below may require research on the web

 Record the questions below and the answers in “prog2.txt”.

1. What is the purpose of the Linux Virtual File System (VFS)?

2. Describe the ext2 filesystem

3. What does is the difference between ext2 and ext3 file systems?

4. What is the purpose of the super-block?

5. What does the super-block contain (provide a list)?

6. What is the “magic number” used for in the super-block?

7. What does the inode contain (provide a list)?

8. The ls command collects its information from the inode of a file. Use the ls command to determine the following information about the file, /bin/zcat, on cs.franklin.edu: a. The inode of /bin/zcat b. The number of physical (hard) links to /bin/zcat

Answer 1

1. Virtual File System(VFS) is an interface between an operating system's kernel and a concrete file system. It is a kernal software layer which handles the system calls related to the file systems.

The main purpose of the Linux Virtual File Sytem is to allow client applications to access different types of file systems in a proper way.

2. ext2 filesystem(Second Extended File system )

ext2 is the file system for the linux kernal.It uses blocks as the basic unit of storage.

• A disk, file or block device formated with a Second Extended Filesystem is divided into small groups called “blocks”.
• These blocks are then grouped into larger units called block groups.
• Each group duplicates information critical to the integrity of the file system.

3.

ext2

ext3

Stands for Second Extended File system .	Stands for Second Extended File system.
Ext2 does not have journaling feature.	Ext2 have journaling feature.
Overall ext2 file system size can be from 2 TB to 32 TB.	Overall ext3 file system size can be from 2 TB to 32 TB.
Maximum individual file size can be from 16 GB to 2 TB.	Maximum individual file size can be from 16 GB to 2 TB.
It was introduced in 1993.	It was introduced in 2001.

journaling feature: Journaling filesystem keeps a log of the changes that are being made to the filesystem during disk writing .

4. Super block is a data structure in a filesystem .The purpose of the superblock is that it holds metadata about the filesystem, includes

• Which inode is the top-level directory
• Type of filesystem used.

5. Super block stores important information about the file system. It includes

• Blocks in the file system.
• Configuration of the file system.
• Inodes per block group.
• The operating system in which the file system was formatted.
• Blocks per block group.
• No of times the file system was mounted since last fsck.
• Write time.
• No of free blocks in the file system.
• File System State .
• The file system type (ie: ext2,3 or 4).

6. Magic number is a sequence of bytes that is used in files of certain format, usually at a given position . Magic number is used to recognize what format a file is in.

7. The index node(inode)is a data structure that describes a file-system object such as a file or a directory. inode stores the attributes and disk block locations of the object's data.

inode includes:

• File type (executable, block special etc)
• Permissions (read, write etc)
• Owner
• Group
• File Size
• File access, change and modification time
• File deletion time
• Number of links (soft/hard)
• Access Control List (ACLs)

8. cd /bin/zcat ( to change directory )

a) ls -i (To find inode number)

b) ls -l (To find number of hardlinks to a particular inode)