Centos / Fedora / Linux / RHEL7

Master The Skills Of Linux File System And Be Successful

by Ravi Kumar Ankam · Published July 23, 2016 · Updated July 23, 2016

Linux file system is a method to partition the Hard Disk drive into multiple partitions. Partitions are used to store the data by making Linux File System in it. Basically Linux File systems are two types as shown below

Linux File System

Local File Systems are used to format partitions into usable without making file system in partitions we can’t store data. Just making the partitions will turn them as RAW. Partitions are used to organize users data on a Hard Disk.

When you make an Extended File System it will create an different types off blocks to segregate data store

Master Blocks / Boot Blocks
Super Blocks
Inode Blocks
Data Blocks

Master Blocks / Boot Blocks : Only boot partitions contain master blocks data. Remaining partitions master blocks are empty.

Super Blocks : Just like an index to the book and it works holds to the information as follows

Utilized inode numbers
Free inode numbers
Utilized data blocks
Free data blocks

Inode table (index table) which holds all the information about files/directories like permissions, owner, group name, size and time stamps.

4096 bytes default block size
15 data blocks = inode

If data size is more than 100MB block size is 4096bytes. If data size is less than 100MB block size is 1024bytes.

Data block storage of files

Below is the File System comparison in brief

File System	Max File Size	Max Partition Size	Journal-ling	Notes
Fat16	2 GB	2 GB	No	Legacy
Fat32	4 GB	8 TB	No	Legacy
NTFS	2 TB	256 TB	Yes	(For Windows Compatibility) NTFS-3g is installed by default in Ubuntu, allowing Read/Write support
ext2	2 TB	32 TB	No	Legacy
ext3	2 TB	32 TB	Yes	Standard linux filesystem for many years. Best choice for super-standard installation.
ext4	16 TB	1 EB	Yes	Modern iteration of ext3. Best choice for new installations where super-standard isn’t necessary
reiserFS	8 TB	16 TB	Yes	No longer well-maintained
JFS	4PB	32PB	Yes (metadata)	Created by IBM – Not well maintained
XFS	8 EB	8 EB	Yes (metadata)	Created by SGI. Best choice for a mix of stability and advanced journaling
GB= Gigabyte (1024 MB) TB = Terabyte (1024 GB) PB = Petabyte (1024 TB) EB = Exabyte (1024 PB)

How the Partitions take place

Always partitions can be four at any point of time

Primary =3 and Extended =1 OR Primary=4

if you create an partition, numbers will be assigned as mentioned below

All primary partitions will directly assign 1 – 4 numbers, whereas 3 primary 1 extended will create like below. Extended partition number 4 just created we can’t make any file system on that.

To Create partitions we have to use fdisk utility

[root@Techtutorials ~]# fdisk /dev/sdc
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): n
All primary partitions are in use
Adding logical partition 6
First sector (825344-10485759, default 825344):↵
Using default value 825344
Last sector, +sectors or +size{K,M,G} (825344-10485759, default 10485759): +100M
Partition 6 of type Linux and of size 100 MiB is set

Command (m for help): p

Disk /dev/sdc: 5368 MB, 5368709120 bytes, 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xead8a888

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1            2048      206847      102400   83  Linux
/dev/sdc2          206848      411647      102400   83  Linux
/dev/sdc3          411648      616447      102400   83  Linux
/dev/sdc4          616448    10485759     4934656    5  Extended
/dev/sdc5          618496      823295      102400   83  Linux
/dev/sdc6          825344     1030143      102400   83  Linux

Command (m for help): wq
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.

by default when you create an extended partition it will not update kernel to update kernel we have to execute below command

# partprobe /dev/sdc
[root@Techtutorials ~]# mkfs.ext4 /dev/sdc1
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
25688 inodes, 102400 blocks
5120 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=33685504
13 block groups
8192 blocks per group, 8192 fragments per group
1976 inodes per group
Superblock backups stored on blocks:
        8193, 24577, 40961, 57345, 73729

Allocating group tables: done
Writing inode tables: done
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

Mount partition

Partition has been formatted with EXT4, to mount it permanently we have to add an entry in /etc/fstab file.

[root@Techtutorials ~]# mkdir /data
[root@Techtutorials ~]# vi /etc/fstab
[root@Techtutorials ~]# cat /etc/fstab

#
# /etc/fstab
# Created by anaconda on Wed Jun 22 11:14:58 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/rhel-root   /                       xfs     defaults        0 0
UUID=5b0f4ed0-592e-4114-9a8e-10a7b99d2cd3 /boot                   xfs     defaults        0 0
/dev/mapper/rhel-swap   swap                    swap    defaults        0 0
/dev/sdc1       /data   ext4 defaults 0 0
[root@Techtutorials ~]# df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root   18G  3.3G   15G  19% /
devtmpfs               1.2G     0  1.2G   0% /dev
tmpfs                  1.2G   80K  1.2G   1% /dev/shm
tmpfs                  1.2G  8.9M  1.2G   1% /run
tmpfs                  1.2G     0  1.2G   0% /sys/fs/cgroup
/dev/sda1              497M  124M  373M  25% /boot

[root@Techtutorials ~]# mount -a
[root@Techtutorials ~]# df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root   18G  3.3G   15G  19% /
devtmpfs               1.2G     0  1.2G   0% /dev
tmpfs                  1.2G   80K  1.2G   1% /dev/shm
tmpfs                  1.2G  8.9M  1.2G   1% /run
tmpfs                  1.2G     0  1.2G   0% /sys/fs/cgroup
/dev/sda1              497M  124M  373M  25% /boot
/dev/sdc1               93M  1.6M   85M   2% /data

To mount partition temporarily we have to use below command mount and unmount partition using umount

[root@Techtutorials ~]# mount /dev/sdc1 /data
[root@Techtutorials ~]# df -h /data
Filesystem      Size  Used Avail Use% Mounted on
/dev/sdc1        93M  1.6M   85M   2% /data
[root@Techtutorials ~]# umount /data

To Delete Partition follow below steps

unmount file system
Remove entry from fstab file
delete partition
Update kernel

[root@Techtutorials ~]# umount /data
[root@Techtutorials ~]# vi /etc/fstab
[root@Techtutorials ~]# mount -a
[root@Techtutorials ~]# cat /etc/fstab |grep /dev/sdc
##/dev/sdc1     /data   ext4 defaults 0 0
[root@Techtutorials ~]# fdisk /dev/sdc
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): d
Partition number (1-6, default 6): 1
Partition 1 is deleted

Command (m for help): p

Disk /dev/sdc: 5368 MB, 5368709120 bytes, 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xead8a888

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc2          206848      411647      102400   83  Linux
/dev/sdc3          411648      616447      102400   83  Linux
/dev/sdc4          616448    10485759     4934656    5  Extended
/dev/sdc5          618496      823295      102400   83  Linux
/dev/sdc6          825344     1030143      102400   83  Linux

Command (m for help): wq
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[root@Techtutorials ~]# partprobe /dev/sdc

Conclusion

Standard partition can be created using fdisk utility. Standard Linux File system can’t be increased/decreased which is not flexible for production environment.

That’s it about Linux File System

Related Articles

Linux Boot process

Linux Swap File System

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Tags: Linux file system

Ravi Kumar Ankam

My Name is ARK. Expert in grasping any new technology, Interested in Sharing the knowledge. Learn more & Earn MoreView all Posts

prasanthreddy says:
August 13, 2016 at 5:16 am
what is mountpoint? what will be happend after formatting partition?what is filesytem?

Reply
- Ankam Ravi Kumar says:
  August 13, 2016 at 5:48 am
  mount point is just directory, simple way is entrance door for home. when you format an partition it will create various blocks to accommodate data.
  
  Reply