The computer file system is the
method of organizing how and where the data should be stored on the hard disk,
accessed, and managed. The computer file system also provides the capabilities
to modify, create, delete the files. Without the file system, the information
which is stored would not be isolated into individual files and would be
difficult to identify and retrieve.
The ext, ext2, ext3, ext4, and xfs
are all the file systems created for the Linux operating system.
1. Ext -
The ext stands for extended file system and first implemented in 1992 as the
file system created specifically for the Linux. It was developed by Remy Card.
Its metadata structure was inspired by the UFS (UNIX file system). It was
designed to overcome the certain limitations of the MINIX file system. The
individual file size can be 2GB.
2. Ext2 - The ext2 stands for the second
extended file system and it was first introduced in 1993. It was developed to
overcome the limitation of the ext file system. It was also developed by Remy
Card. This file system does not support the journaling feature. This file
system comes with the fundamental concept of inode number (index node number or
index node). Every file in the file system is represented by an inode. The inode
structure contains the pointer to the file system blocks which contains the
details about the file and all the meta-data.
The individual file size can be from 16 GB to 2 TB maximum and the
overall file system size can be from 2 TB to 32 TB.
3. Ext3 -
The ext3 stands for the third extended file system and it was developed by
Stephen Tweedie in 2001. It was introduced in Linux kernel 2.4.15 and available
since then. It also introduces the journaling feature. Journaling is developed
to prevent data from corruption through sudden power loss or system crashes. There
is three types of journaling mode are available in the ext3 file system such as
journal, ordered, and write back.
- Journal - It provides the most secure data retention policy. Basically, it writes metadata and file
content to the journal but reduces the performance.
- Ordered - This is a default mode and all the metadata are journal only after writing the content to disk.
- Write back - This mode is faster
but at high risk. It makes no guarantee as to when the metadata is committed to the journal. But allow the file to shows up after a crash and relies on
kernel standard write back to flush buffers
The conversion from ext2 to ext3 the file system is possible
directly without and backups or restore by using “tune2fs command”.
4. Ext4 - The
ext4 stands for the fourth extended file system it was developed in 2008 and
introduced in Linux kernel 2.6.14 and available since then. It has a backward
compatibility feature means the ext4 can convert into ext3 or ext2. There are
several more features are introduced in the ext4 file system such as
multi-block allocation, journal checksum, fast fsck (file system check),
delayed allocation, etc. In the ext4 user have an option to turn off the
journaling features. The maximum size of an individual file can be from 16 GB
to 16 TB and the overall file system size is 1 EB (Exabyte) which is greater
than 1 PB (Petabyte) = 1024 TB and 1 TB (Terabyte) = 1024 GB.
5. XFS - The
xfs file system was developed by Silicon Graphics Incorporation (SGI) in 1994.
This is a 64-bit high-performance journaling file system and introduces in SGI’s
IRIX operating system but with version 5.3. This file system was introduced to
the Linux kernel in 2001 but in 2014 the xfs file system is supported by most
of the Linux distributions and some use as a default file system. The maximum
size of an individual file is 8 EB (Exabyte) for the 64-bit file system. The
xfs file system is highly scalable but its scalability is for only scaling up
not for scaling down means once you create a file system with xfs you cannot
reduce the size
Note: Microsoft’s FAT file system is also
often an option when formatting a driver in the Linux
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