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2wowthings · 5 years ago

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LINUX FILE SYSTEM

Linux File System (Directory Structure)

Linux is not the complete OS it is a number of packages built around a kernel. It has too many lines of code invented and developed by Mr. Linux Torvald in 1991. Developers can edit the code as it was released under open source and free for others.

The Linux file system is a mixture of folders or maybe directory. Everything in Linux is FILE. It is in form like a tree structure start with / directory. Each partition under the root directory.

TYPES OF LINUX FILE SYSTEM

ext2 Linux file System

ext3

Linux file System

ext4

Linux file System

JFS

Linux file System

ReiserFS

Linux file System

XFS

Linux file System

btrfs

Linux file System

swap

Linux file System

ext2 Linux File System

ext2 stands for the second extended file system it was included in 1993.developed to overcome of limitation of the ext file system. It does not have a journaling feature. Maximum individual file size supports from 16 GB to 2 TB and overall ext2 file system size is 2 TB to 32 TB

ext3 Linux File System

ext3 stands for the third extended file system. Introduced in 2001 starting from Linux kernel 2.4.15 and onwards. The main benefit is to allow journalling. It is a dedicated area in the file system where all changes are tracked when the system crash the possibility of file system corruption is less because of the journaling feature. Maximum individual file size supports from 16 GB to 2 TB and overall ext3 file system size is 2 TB to 32 TB. Three types of journaling available in the ext3 file system.

1 - Journal Metadata and content save in journal

2 - Ordered Only metadata save in journal, metadata are journaled only after writing the content to disk and this is the default.

3 - Writeback Only metadata save in journal. Metadata journaled either before or after the content is written to disk.

ext4 Linux File System

ext4 stands for fourth extended file system and it is introduced in 2008. Supports 64000 subdirectories in one directory. Maximum individual file size supports from 16 GB to 16 TB and overall ext4 file system size is 1 exabyte

1 exabyte = 1024 PB

1 PB = 1024 TB

Here we have the option to switch off journalling features on or off.

JFS Linux file system

JFS is Journaled File System and developed by IBM. It can be an alternative to the EXT file system.

ReiserFS Linux file system

ReiserFS is an alternative for the EXT3 file system.

XFS Linux file system

XFS file system considered as high-speed JFS was developed for parallel I/O processing

btrfs Linux file system

btrfs file system is a b tree file system. using for fault tolerance, storage configuration, and many more.

swap Linux file system

the swap file system is used for memory paging with equal to system RAM size

LINUX FILE SYSTEM HIERARCHY

ve Diagram explained itself about all directories

Linux-file-systen

(Image Credit) Image Source - Google | Image By - Austinvernsonger

Few details of the above diagram

/ directory ( root directory)

Everything on Linux located under the / directory also known as the root directory. It is similar to windows C:\ directory difference is Linux not having drive letters, on windows, it is D:\ but on Linux another partition under / directory

/bin directory (user binaries)

This directory contains some of the standards commands of files. this may be useful for all the users also no special root or su permission required.

/sbin directory (system administration binaries)

/sbin directory is similar to the almost /bin directory. It contains essentials system administration commands files. Only run by root or super user.

/etc directory (configuration files)

This directory contains system configuration files.

/dev directory (device file)

This directory contains device files. These all files associated with the device. Everything in Linux is a file.

/proc directory (kernel and process files)

This directory similar to /dev, It contains a special file that represents system and process information.

/var directory (variable data files)

This directory contains variable data files such as printing jobs.

/tmp directory (temporary files)

All the application store their temporary files in /tmp directory. these can be deleted after the system restarts.

/usr directory (user binaries and read-only data)

This contains user applications software files, libraries for a programming language, document files.

/home directory (users home directory)

This directory is having the home folder for each user created. This also contains users data files and user-specific configuration files

/boot directory (boot files)

This directory contains Linux boot loader files

/lib directory (essentials shared libraries)

This directory contains libraries needed by essentials binaries in the /bin and /sbin directory

/opt directory (optional package)

This directory contains subdirectories for optional software package

/mnt directory (temporary mount files)

This directory has system administrator temporary files mounted on /mnt

/media directory (removable media)

This directory contains subdirectories where removable media device inserted into the computer are mounted

/srv directory (service data)

It is having data for service provided by the system example website files under /srv (https server)

We see working in details

First, we check fdisk command here

fdisk /dev/sda ( checking hard disk by using fdisk command)

We will get output like below

command (m for help): p (type p here for cheeking the details)

Gives us all partition details

/dev/sda1

/dev/sda2

/dev/sda3

like this details about partitions

Now creating new partition we can use option n

type n and hit enter

assigning cylinder value and partition size

then save this partition with option w

now changing the partition type using option t

type t hit enter

now select partition number example 9 hit enter

type l for option

83 is linux file system

type 83 and hit enter

to check type p and hit enter

type w for save and hit enter

Now check fdisk -l /dev/sda ( it will show us created partition)

The kernel must know this created partition so we use below command to update

partprobe

and

kpartx -a /dev/sda; kpartx -l /dev/sda

We can check cat /proc/partition the new partition in this way

CREATING FILE SYSTEM

mkfs.ext4 /dev/sda8 (using this command we define file system type)

mke2fs -j -L data -b 2048 -i 4096 /dev/sda8

here are -L filesystem label

-j journaling

-b block size

-i inode per every 4kb of disk space

LABELING TO LINUX FILE SYSTEM

e2label

(Using this command we can give a name to file system)

e2label /dev/sda8 data

(here we have give the name data to /dev/sda8)

If we want to use this new partition we need to mount the partition

MOUNTING OF NEW LINUX FILE SYSTEM

mount LABEL=data /admin

TO CHECK LABELS AND TYPE OF ALL FILE SYSTEM

blkid (This is the command we can check type of file system)

MANAGE PARAMETERS OF LINUX FILE SYSTEM

dumpe2fs /dev/sda8 (this show all below details please check example)

file system flags

default mount option

block count

block size

first block

inode count

last mounted on

UUID

file system magic number

EXCLUDE FSCK CHECK FOR PARTICULAR LINUX FILE SYSTEM WHILE BOOTING

tune2fs -i0 -c0 /dev/sda8 (this partition exclude while booting for fsck check purpose)

MOUNT POINT LINUX FILE SYSTEM

We will mount the partition in /etc/fstab file

device mount point fs type options dump_freq fsck_order

LABEL=data /admin ext4 defaults 0 0

Understand what is this mean

device device name

mount point path for using access to file system

fs type of file system

options comma-separated list of different options can use

dump_freq it is 1=daily, 2=every next day, 0=never dump

fsck_order 0=ignore and 1=first and from 2-9=second,third

We can use command mount -a and check df -h for checking the mounted partition

DENY ACCESS TO PARTICULAR FOLDER OF LINUX FILE SYSTEM WHICH IS MOUNTED

mount -t ext4 -o noexec /dev/sda8 /admin

INCREASE I/O PERFORMANCE OF LINUX FILE SYSTEM

mount -t ext4 -o noatime /dev/sda8 /admin

UMOUNT LINUX FILE SYSTEM

We need to exit from partition and then need to use below command

umount /admin

CREATING SWAP PARTITION

fdisk -l /dev/sda

Check for the partition available or create using n command for new as we have discussed above

mkswap /dev/sda10 (creating swap using mkswap the command for sda10)

Update in fstab

vim /etc/fstab

device mount point fs type options dump_freq fsck_order

/dev/sda10 swap swap defaults 0 0

save this file and exit

Now

swapon -a

swapon -s

CREATING SWAP FILE

dd if=/dev/zero of=/swapfile bs=1024 count=100000 (will create swap file)

Now

mkswap /swapfile

Update in fstab

device mount point fs type options dump_freq fsck_order

/swapfile swap swap defaults 0 0

save and exit the file

swapon -a

swapon -s

Now we have created swap partition as well file

This is LINUX FILE SYSTEM It is more in deep ANYTHING PLEASE CONTACT ME SUBSCRIBE FOR NEW UPDATES

THANKS TO ALL GOD BLESS

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