Partitioning the drive

Now that the Arch live ISO has been connected to the internet, you’ll need to divide your disk up into partitions.

This guide will show you how to create four different partitions:

• A boot partition, which holds the files that load the kernel and other necessary things for your computer to enter a state where it can be used.
• A swap partition, which holds swap space
• A root partition, which holds your root directory
• A home partition, which holds your user account and anything that might be stored on to it, like images and documents.

Partitioning the drive

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Firstly, enter the gdisk shell (which is a program that helps you manage modern drives), as shown below:

# gdisk <your drive>

This will change your shell prompt from:

root@archiso ~ # 

to

Command (? for help):

Enter “expert mode” as shown below (expert mode allows you to do more things with your drive):

Command (? for help): x

Which changes your prompt to this:

Expert command (? for help):

Delete everything on your drive using the below command:

Expert command (? for help): z

This will bring up a warning message to confirm this is absolutely, positively what you want to do.
Enter “y” to confirm.

About to wipe out GPT on {your drive}. Proceed (Y/N): y

Another message will pop up:

GPT data structures destroyed! You may now proceed to partition the disk using fdisk or other utilities.
Blank out MBR? (Y/N):

Enter “y” to confirm the above. This will overwrite the first 512 bytes of your drive so that any bootloader you install later on will not get confused.

After clearing your drive, gdisk will return you to your regular shell prompt (as seen below):

root@archiso ~ # 

Return to the gdisk shell by entering:

# gdisk <your drive>

Changing your prompt back to:

Command (? for help):

You will want to create partitions for Arch Linux to live on. This can easily be done by entering the following commands.

Firstly, you want to create a boot partition (as shown below):

Command (? for help): n

gdisk will then ask you what number you want to give this partition, as shown below.

Partition number (1-128, default 1): 

Simply press enter when it prompts you with the above. Here, gdisk just gives the partition the next unused number.

Next, gdisk will ask you where you want the partition to begin.

First sector (<...>, default=2048) or {+-}size{KMGTP}: 

Press enter to begin the partition at the first bit of free space it can allow.

Then, gdisk will ask how big you want the partition to be (as shown below).
1 gigabyte is more than enough for a boot partition.

Last sector (<...>, default=<...>) or {+-}size{KMGTP}: +1G

It will then ask you what type of partition you want to create.
We want to create a modern boot partition. So enter ‘EF00’ as shown below.

Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300): EF00

It will then return you to:

Command (? for help):

You will want to set a “label” for this partition - a unique name to help you identify this partition.
For the purposes of this guide, it will be labelled as “boot”

Command (? for help): c

gdisk will then ask you which partition you want to label. Select partition 1

Partition number (1-1): 1

Then it will ask you to set the label for this partition. Enter boot

Enter name: boot

This time, you will want to create a swap partition.
Create a new partition as shown below.

Command (? for help): n

gdisk will then ask you what number you want to give this partition, as shown below.
Hit enter to use the default.

Partition number (2-128, default 2): 

Next, gdisk will ask you where you want the partition to begin.
Hit enter to use the default.

First sector (<...>, default=<...>) or {+-}size{KMGTP}: 

Then, gdisk will ask you how big you want the partition to be.
The size of this partition will depend on how big your RAM is. Make your swap partition twice the size of your RAM, or use 16 gigabytes, whichever is smaller.
The below is for if your RAM is 16 gigabytes or larger.

Last sector (<...>, default=<...>) or {+-}size{KMGTP}: +16G

It will then ask you what type of partition you want to create.
We want to create a swap partition. So enter ‘8200’ as shown below.

Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300): 8200

Now, you will want to name this partition swap.\

Command (? for help): c

Enter the number for the swap partition (2):

Partition number (1-2): 2

Then name it swap

Enter name: swap

Now, you want to create a partition for your system files to live in (your root partition)

Command (? for help): n

Press enter to the below prompts to use their defaults:

Partition number (3-128, default 3): 

And:

First sector (<...>, default=<...>) or {+-}size{KMGTP}: 

Now for the size of your root partition. If your drive is small (less than 128GB), press enter to the below prompt to use up the rest of your drive. This will mean that your system files and things like documents will live in the same space on your drive.

Last sector (<...>, default=<...>) or {+-}size{KMGTP}:

If your drive is 128GB in size or higher, then give your root partition 40GB in space.

Last sector (<...>, default=<...>) or {+-}size{KMGTP}: +40G

Simply press enter when given the below prompt, to tell your computer that this is just a regular filesystem partition.

Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300):

Now, you will want to name this partition root.

Command (? for help): c

Enter 3 to the below prompt to select the root partition.

Partition number (1-3): 3

Then, name it root.

Enter name: root

Command (? for help): n

Partition number (4-128, default 4): 

First sector (<...>, default=<...>) or {+-}size{KMGTP}: 

Last sector (<...>, default=<...>) or {+-}size{KMGTP}:

Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300):

Command (? for help): c

Partition number (1-4): 4

Enter name: home

These partitions have been created, but have not actually been written to the drive.
gdisk has only kept track of them in memory.
To actually write them to drive, enter the below command:

Command (? for help): w

gdisk will confirm with you to ensure that you want to write these partitions to your drive.
Enter y to confirm these changes.

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING PARTITIONS!!

Do you want to proceed? (Y/N): y

You should then see the following message:

OK; writing new GUID partition table (GPT) to <your drive>
The operation has completed successfully

Then you will be returned to the shell prompt (see below)

root@archiso ~ # 

Formatting partitions

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Now that these partitions have been created, it is now time to make them actually useable.
To do this, you will have to format the partitions.

For most users, there are two filesystems that you can format your root (and home, if applicable) partition(s) to: btrfs and ext4.

Btrfs offers snapshots and checksumming. Snapshots are like freeze-frames of your entire filesystem so that if you screw something up, you can easily restore your files to how they were to some point in time before you screwed things up.

Checksumming just ensures that your data hasn’t been maliciously tampered with.

ext4 doesn’t have these things, but it is quite fast and is the most common filesystem you will find on Linux.

Check that your partitions are correct by typing in the below command:

# lsblk

Format the boot partition, as shown below:

# mkfs.fat -F32 /dev/disk/by-partlabel/boot

Then, format the swap partition, as shown below:

# mkswap /dev/disk/by-partlabel/swap

# cryptsetup luksFormat /dev/disk/by-partlabel/root

WARNING!
========
This will overwrite data on /dev/disk/by-partlabel/root irrevocably.

Are you sure? (type 'yes' in capital letters): YES

Enter passphrase:

Verify passphrase:

# cryptsetup luksFormat /dev/disk/by-partlabel/home

Enter passphrase:

Verify passphrase:

# cryptsetup open /dev/disk/by-partlabel/root cryptroot

Enter passphrase for /dev/disk/by-partlabel/root:

# cryptsetup open /dev/disk/by-partlabel/home crypthome

Enter passphrase for /dev/disk/by-partlabel/home:

# mkfs.btrfs /dev/mapper/crypthome -f

# mkfs.ext4 -F /dev/mapper/crypthome

# mkfs.btrfs /dev/mapper/crypthome -f

# mkfs.ext4 -F /dev/mapper/crypthome

Then, format the root partition, as shown below:

# mkfs.btrfs /dev/disk/by-partlabel/root -f

OR, do not run the below command if you have run the one above, or vice versa.

# mkfs.ext4 -F /dev/disk/by-partlabel/root

If you have created a home partition, go ahead and format it.

# mkfs.btrfs /dev/disk/by-partlabel/home -f

OR, do not run the below command if you have run the one above, or vice versa.

# mkfs.ext4 -F /dev/disk/by-partlabel/home

Mounting partitions

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For the partitions to be accessible to the Arch ISO, you need to mount them, which means to make them an accessible location on the Arch ISO.

# mount /dev/mapper/cryptroot /mnt

# swapon /dev/disk/by-partlabel/swap

# mount -m /dev/disk/by-partlabel/boot /mnt/boot

# mount -m /dev/mapper/crypthome /mnt/home

To do this, start by mounting the root partition.

# mount /dev/disk/by-partlabel/root /mnt

Then mount your swap partition:

# swapon /dev/disk/by-partlabel/swap

Then the boot partition:

# mount -m /dev/disk/by-partlabel/boot /mnt/boot

And finally, the home partition:

# mount -m /dev/disk/by-partlabel/home /mnt/home