mkfs Command in Linux: Format Partitions with ext4, XFS, FAT

The mkfs command on Linux formats the partition created by fdisk / gdisk / parted with the file system.

The file system type is defined by the -t option and the native formats are ext2, ext3, ext4, fat, vfat, minix, msdos and xfs.

The mke2fs and mkdosfs commands are variations of mkfs.

mkfs has some variations that allow you to choose the file system type directly:

$ ls -l /usr/sbin/mk*lrwxrwxrwx 1 root root      8 ago 29 22:48 /usr/sbin/mkdosfs -> mkfs.fat-rwxr-xr-x 4 root root  96328 jul 26  2018 /usr/sbin/mke2fs-rwxr-xr-x 1 root root  11432 jul 26  2018 /usr/sbin/mkfs-rwxr-xr-x 4 root root  96328 jul 26  2018 /usr/sbin/mkfs.ext2-rwxr-xr-x 4 root root  96328 jul 26  2018 /usr/sbin/mkfs.ext3-rwxr-xr-x 4 root root  96328 jul 26  2018 /usr/sbin/mkfs.ext4-rwxr-xr-x 1 root root  28512 ago  2  2018 /usr/sbin/mkfs.fat-rwxr-xr-x 1 root root  83824 jul 26  2018 /usr/sbin/mkfs.minixlrwxrwxrwx 1 root root      8 ago 29 22:48 /usr/sbin/mkfs.msdos -> mkfs.fatlrwxrwxrwx 1 root root      8 ago 29 22:48 /usr/sbin/mkfs.vfat -> mkfs.fat-rwxr-xr-x 1 root root 372448 jan 24  2019 /usr/sbin/mkfs.xfs

Depending on the variation you choose, mkfs may have more or fewer options.

In general, the possible options for the mkfs command are:

• -t: Specifies the formatting type for the partition
• -c: Checks for bad blocks (defects) on the device;
• -L: name Sets the device name;
• -n: name Sets the device name for msdos format;
• -q: Makes mkfs work with minimal output to the screen;
• -v: Makes mkfs work with maximum output to the screen;
• -m: Percentage of reserved disk space

An interesting option of mkfs is "-m percentage" which allows you to reserve a portion of the disk in percentage to prevent the system from freezing in case the disk is full. The idea is for the operating system to alert that the disk is full to regular users BEFORE the disk is actually completely full. This allows the system to continue functioning for a while until the administrator can take some action to prevent a truly full disk from freezing the system or causing data loss.

Example:

Formats with ext3 file system:

# mkfs.ext3 /dev/xvdb1mke2fs 1.42.9 (28-Dec-2013)Filesystem label=OS type: Linux

Block size=4096 (log=2)Fragment size=4096 (log=2)Stride=0 blocks, Stripe width=0 blocks524288 inodes, 2096891 blocks104844 blocks (5.00%) reserved for the super userFirst data block=0Maximum filesystem blocks=214748364864 block groups32768 blocks per group, 32768 fragments per group8192 inodes per groupSuperblock backups stored on blocks: 	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632Allocating group tables: done                            Writing inode tables: done                            Creating journal (32768 blocks): doneWriting superblocks and filesystem accounting information: done

Formats the disk with xfs:

# mkfs.xfs  /dev/xvdb1meta-data=/dev/xvdb1             isize=512    agcount=4, agsize=524223 blks         =                       sectsz=512   attr=2, projid32bit=1         =                       crc=1        finobt=1, sparse=0data     =                       bsize=4096   blocks=2096891, imaxpct=25         =                       sunit=0      swidth=0 blksnaming   =version 2              bsize=4096   ascii-ci=0 ftype=1log      =internal log           bsize=4096   blocks=2560, version=2         =                       sectsz=512   sunit=0 blks, lazy-count=1realtime =none                   extsz=4096   blocks=0, rtextents=0

File Systems

Once the partitions are already defined, you can create the File System that will be used. Linux supports several file systems and your choice depends a lot on the intended use of the system and the disk type.

Disks formatted with ext2, ext3 and ext4 have a wide range of tools. Since they use a fixed block size, they are not good file systems for small files, as they may consume a lot of disk space unnecessarily.

For example, ext4 uses 4K blocks by default. If you have many small files like 1k, each file will use an entire 4k block, even if its size is smaller than that.

XFS on the other hand is excellent at performing parallel input/output (I/O) operations using multiple physical disks, as it was designed for high performance of graphical workstations. It is ideal for applications that edit images and videos.

BTRFS on the other hand seems to be the most correct choice, as it allows snapshots, compression, defragmentation and so many other advantages, but it is not always available in all distributions.

The following table will help you choose the file system:

File System Type	Suggested Use	Advantages	Disadvantages
ext2	Used in /boot and on USB drives	Simple and fast	No journaling
ext3	General use on Linux	Adds Journaling to ext2 without needing to format	Not as fast and reliable as ext4
ext4	General use on Linux	Better performance and reliability than ext3	Does not allow a series of features that BTRFS has
XFS	General use on Linux	Better performance than ext3. Ideal for videos.	Does not allow a series of features that BTRFS has
ReiserFS	No longer used	Efficient for small files	High CPU consumption
VFAT	Memory cards and USB drives	Easy portability with Windows	All of them :-)
BTRFS	General use on Linux	All of them :-)	Virtually none

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