How to Use the Command 'mke2fs' (with examples)

The mke2fs command is a utility in Linux used to create filesystems on a block device, typically a partition on a hard disk. This command formats the specified partition with the chosen filesystem type, allowing the operating system to store and manage files appropriately on that partition. The mke2fs utility is pivotal in preparing disk partitions for usage, whether it’s setting up a new system or adding additional storage to an existing one. It supports various ext filesystem types, including ext2, ext3, and ext4, each providing different features and benefits.

Use case 1: Creating an ext2 filesystem

Code:

mkfs.ext2 /dev/sdb1

Motivation:

The ext2 filesystem is one of the earliest types of filesystems used in the Linux ecosystem. Its simplicity and reliability make it suitable for use in scenarios where journaling is not required, such as in flash drives or very small partitions where the overhead of journaling is undesired. Ext2 might also be preferred in environments where minimal resources are necessary, or if compatibility across different systems is prioritized due to its older, stable nature.

Explanation:

• mkfs.ext2: This is the command to format the partition with an ext2 filesystem. The mkfs utility is a frontend to mke2fs, which also supports other filesystem types. The extension .ext2 specifically invokes the creation of an ext2 file structure.
• /dev/sdb1: This specifies the target partition where the filesystem will be created. /dev/sdb1 indicates partition 1 on the device sdb, typically a secondary hard drive or similar attached storage. It’s necessary to ensure that this partition is unmounted before executing the command to avoid data corruption.

Example output:

mke2fs 1.45.6 (20-Mar-2020)
Creating filesystem with 102400 1k blocks and 25688 inodes
Filesystem UUID: e88ac4b5-c747-4b6e-a2f5-00498daba2b8
Superblock backups stored on blocks: 
8193, 24577, 40961, 57345, 73729

Allocating group tables: done                            
Writing inode tables: done                            
Writing superblocks and filesystem accounting information: done

Use case 2: Creating an ext3 filesystem

Code:

mkfs.ext3 /dev/sdb1

Motivation:

The ext3 filesystem adds journaling capabilities to ext2, improving reliability and crash recovery by keeping track of changes not yet committed to the filesystem’s main part. This is especially beneficial in environments where systems cannot afford unscheduled downtime, or where rapid recovery is crucial after a crash. It balances performance and robustness, making it suitable for most general-purpose Linux deployments.

Explanation:

• mkfs.ext3: This command formats the specified partition with an ext3 filesystem. It invokes the mkfs utility specifically to use the ext3 filesystem driver, which includes support for journaling.
• /dev/sdb1: Indicating the specific partition to format, /dev/sdb1 is the target for the filesystem creation, part of the /dev directory that conventionally lists all block devices on the system. As with any filesystem creation task, ensuring the partition is not mounted is crucial to prevent data issues.

Example output:

mke2fs 1.45.6 (20-Mar-2020)
Creating filesystem with 102400 1k blocks and 25688 inodes
Filesystem UUID: d1c97aac-a98b-4fb6-bc5d-745d2bdb56e7
Superblock backups stored on blocks: 
8193, 24577, 40961, 57345, 73729

Allocating group tables: done    
Writing inode tables: done    
Creating journal (1024 blocks): done
Writing superblocks and filesystem accounting information: done

Use case 3: Creating an ext4 filesystem

Code:

mkfs.ext4 /dev/sdb1

Motivation:

Ext4 is the successor to both ext2 and ext3, providing improvements in performance, large file support, and speed of filesystem checks, along with extended capacities. It allows for backwards compatibility with ext3 and ext2 while offering significant advancements, making it the default choice for modern Linux distributions. When working with systems that demand high performance and efficiency, along with the capability of handling large volumes of data, ext4 is an optimal choice.

Explanation:

• mkfs.ext4: Executes the formatting of a partition with an ext4 filesystem. Invoking the mkfs command with the .ext4 extension calls upon the ext4 driver, which includes advanced features like extents, multiblock allocation, and faster fsck times.
• /dev/sdb1: Denotes the specific partition to be formatted as ext4. Careful usage of /dev/sdb1 is necessary to ensure correct partition formatting.

Example output:

mke2fs 1.45.6 (20-Mar-2020)
Creating filesystem with 102400 1k blocks and 25688 inodes
Filesystem UUID: 6d97d57c-c6e8-4f5f-bb64-c70b2f8c420a
Superblock backups stored on blocks: 
8193, 24577, 40961, 57345, 73729

Allocating group tables: done    
Writing inode tables: done    
Creating journal (1024 blocks): done
Writing superblocks and filesystem accounting information: done

Conclusion

The mke2fs command is a flexible and powerful tool to create various ext filesystems on a Linux system. Whether you are installing a new system, setting up additional storage, or ensuring compatibility with specific environments, understanding the distinct properties and appropriate use cases of ext2, ext3, and ext4 filesystems can lead to making informed, effective decisions regarding data storage needs.