[Wiki] Linux disks

Disks infos

Initializing the Disk

Partition type:

• Primary partition is a bootable partition and it contains the operating
• Extended partition is a partition that is not bootable.

Extended partition typically contains multiple logical partitions and it is used to store data.

Difference:

- Quantity: At least 1 and a maximum of 4.
- Bootable: The primary partition is bootable, and it contains the operating system/s of the computer.
- Applicable scenarios: We can use it to boot the operating system, establish one to four primary partitions and install multiple operating systems without interfering.
- Naming example: Primary partitions are assigned the first letters in the alphabet as drive letters (such as C, D). Logical drives in the extended partition get the other letters (such as E, F, G).

Verifying and Writing Changes

Initializing a Linux Data Disk (fdisk):

 sudo fdisk -l

Partitioning the disk:

sudo fdisk /dev/sdx

Create the partition

#Create a new partition:
  - n

#Primary or extended partition:
  - p
  - e

#Partition number:
  - Usually use the default, 1 to 4 for a primary partition

#First sector:
  - usually default

#Last sector:
  - same

#Verify:
  - p

#Write changes to the disk:
  - w

Run the following command to synchronize the new partition table to the OS:

partprobe

Formatting the Disk

Format the disk to the correct file system format:

mkfs.ext4 /dev/sdx
#or
mkfs -t ext4 /dev/sdx

Mounting the Disk

Mount the disk after formatting:

mount /dev/sdx /mnt/dir

Configuring for Fstab

Find the UUID for fstab provisioning:

blkid /dev/sdx

Add a line to modify fstab and keeping partition change at boot:

UUID=0bdsdsds-1337-4abb-841d-bddd0b92693df /mnt/sdc       ext4    defaults        0 2

Testing Automatic Mount

First: unmount the disk

unmount /dev/sdx

Second: Mount automatically using fstab file

mount -a

Optionnal: Verify the thingy

mount | grep /mnt/sdx

Creating an LVM Disk and Formatting in ext4:

Create Physical Volume (PV)

sudo pvcreate /dev/sdx

Create Volume Group (VG)

sudo vgcreate vg_name /dev/sdx

Create Logical Volume (LV)

sudo lvcreate -L sizeG -n lv_name vg_name

Format the Logical Volume

sudo mkfs.ext4 /dev/vg_name/lv_name

Mount the Logical Volume and Verify:

Create a mount point if necessary

sudo mkdir -p /mnt/lvm

Mount the logical volume

sudo mount /dev/vg_name/lv_name /mnt/lvm

Verify the mount

mount | grep /mnt/lvm

Disk Usage

Disk Usage Commands:

```bash
# Show child directory sizes of current directory in bytes
du

# Show human-readable directory sizes
du -h

# Show size of current directory only (nesting depth=0)
du -d 0

# Show child directory sizes of current directory in MB
du -BM

# Show child directory sizes of the specified directory in bytes
du /path/to/directory

# Show sizes of direct child directories only
du -d 1 .

# Sort directories by size
du -BM -d 1 . | sort -n

# Show sizes of all directories in root (/), sorted in reverse numerical order and view in less
du / | sort -nr | less
```