$ Linux Command

Disk

mke2fs

Create an ext2/ext3/ext4 filesystem.

filesystemext2ext3ext4formatmkfs

Additional Notes

mke2fs creates an ext2, ext3, or ext4 filesystem on a disk partition or other block device. It is the low-level tool behind the more commonly used mkfs.ext2, mkfs.ext3, and mkfs.ext4 commands, which are symbolic links to mke2fs with appropriate defaults.

It configures the filesystem superblock, inode table, block groups, and journal (for ext3/ext4). The filesystem type and features are selected using the -t option or by which command name is used to invoke it.

Syntax

mke2fs [options] device [blocks-count]

Parameters

  • device: The block device to format (e.g., /dev/sda1).
  • blocks-count: The number of blocks on the filesystem. If omitted, the entire device is used.

Common Options

  • -t type: Filesystem type: ext2, ext3, or ext4.
  • -b size: Block size in bytes (1024, 2048, or 4096).
  • -i bytes-per-inode: Bytes per inode, controlling the maximum number of files.
  • -N inodes: Explicitly set the number of inodes.
  • -m reserved-blocks-percent: Percentage of blocks reserved for root (default 5%).
  • -O feature[,feature...]: Enable specific filesystem features.
  • -O ^feature: Disable a filesystem feature.
  • -j: Create an ext3 journal.
  • -J size=size: Set journal size for ext3/ext4.
  • -L label: Set the filesystem volume label.
  • -U UUID: Set the filesystem UUID.
  • -c: Check the device for bad blocks before creating the filesystem.
  • -q: Quiet mode.
  • -F: Force formatting even if the device is in use or appears to have a filesystem.
  • -E options: Extended filesystem options (e.g., stride=, stripe_width=).

Examples

mke2fs -t ext4 /dev/sda1

Create an ext4 filesystem on /dev/sda1.

mke2fs -t ext3 -j /dev/sdb1

Create an ext3 filesystem with a journal.

mke2fs -t ext4 -L "DataVolume" /dev/sdc1

Create an ext4 filesystem with a volume label.

mke2fs -t ext4 -m 2 /dev/sda1

Create ext4 with only 2% reserved blocks for root.

mke2fs -t ext4 -O ^has_journal /dev/sda1

Create an ext4 filesystem without a journal (ext4 without the journal feature).

mke2fs -t ext4 -b 4096 -i 16384 /dev/sda1

Create ext4 with 4096-byte blocks and one inode per 16384 bytes.

Practical Notes

  • Formatting a device destroys all existing data. Double-check the device path.
  • The default inode count is based on the bytes-per-inode ratio (default 16384). For many small files, increase the inode count with a lower -i value.
  • Reserved blocks (default 5%) prevent non-root users from filling the disk completely, which can cause system issues.
  • After formatting, use tune2fs to adjust filesystem parameters without recreating it.
  • For SSDs, consider disabling the journal with -O ^has_journal for performance (at the cost of fsck recovery).