Linux Disk Management: Partitioning, Formatting, and Mounting

Checking Installed Disks

• You can use the ls command to display information about hard disks installed in your computer.
• /dev/sda, /dev/sdb, etc. are hard disks, and /dev/sda1, etc. are partitions.

# ls -l /dev/sd*
brw-rw----. 1 root disk 8,  0 Oct 16 13:12 /dev/sda
brw-rw----. 1 root disk 8,  1 Oct 16 13:12 /dev/sda1
brw-rw----. 1 root disk 8,  2 Oct 16 13:12 /dev/sda2
brw-rw----. 1 root disk 8, 16 Oct 16 13:12 /dev/sdb
brw-rw----. 1 root disk 8, 32 Oct 16 13:12 /dev/sdc

Creating Partitions

• The command to manage partitions is fdisk.
• If you want to manage the partitions of /dev/sdb, use the following commands.

# fdisk /dev/sdb

• If you need help, type m.

• To create a new partition, type n and follow the prompts.

• Type w to apply the changes.

Command (m for help): g
Created a new GPT disklabel (GUID: F13C6D0D-1E30-4448-B015-A61F3AE9EA48).

Formatting

• The command to format is mkfs. For example, to format the /dev/sdb1 partition with the ext4 file system, use the following command.

# mkfs.ext4 /dev/sdb1

• To format to the xfs file system, use the following command.

# mkfs.xfs -f /dev/sdb1

Mounting

• You need to attach the partition to a specific directory to be able to use that partition.
• For example, to mount /dev/sdb1 to the /mnt directory, use the following command.

# mount /dev/sdb1 /mnt

• To unmount, use the umount command. There are two methods.

# umount /dev/sdb1
# umount /mnt

• To have it automatically mount at boot, add the following code to the /etc/fstab file.
• This means to mount the /dev/sdb1 partition to the /mnt folder. Adjust options such as the file system as appropriate.

/dev/sdb1 /mnt xfs defaults 0 0

• If you want to immediately apply the changes made to the fstab file, use the following command.

# mount -a

Using UUID

A hard disk gets a name like /dev/sdb, and a partition gets a name like /dev/sdb1, but these names are not fixed. If you change the hard disk's mounting location or the recognition order changes, those names can also change. In such cases, mounting may not work properly. Therefore, when using fstab to mount, it is better to use the hard disk's unique value, the UUID.

• You can check the UUID with the blkid command.

# blkid
/dev/sda1: UUID="69d9add5-2153-4bc2-ad99-1560fb205c4b" TYPE="ext4" PARTUUID="aa61ba4b-01"
/dev/sda2: UUID="PuMuNg-5YHg-qikJ-tc10-iPIM-7W1q-4fUqyc" TYPE="LVM2_member" PARTUUID="aa61ba4b-02"
/dev/mapper/cl-root: UUID="79c8cfcb-c9e2-4243-8cf2-cf10eab57c40" TYPE="xfs"
/dev/mapper/cl-swap: UUID="b69a5fc3-98db-4a27-b3d4-a7ef76244ad1" TYPE="swap"
/dev/mapper/cl-home: UUID="fd372a6b-ee76-41d6-b7e6-6e6a7cf8193b" TYPE="xfs"
/dev/sdb1: UUID="fd95c93f-03fc-418a-a6db-c26b921ec93b" TYPE="xfs" PARTUUID="e5f55ef6-01"

• When adding mount information to /etc/fstab, include the UUID information as follows.

UUID=fd95c93f-03fc-418a-a6db-c26b921ec93b /home xfs defaults 0 0