Creating a BTRFS filesystem on Proxmox (Debian)

First we need to locate the block level device we're going to use, so lsblk and locate it. In this example we'll use /dev/sdb

Install parted

apt install -y parted

Create a Partition

parted /dev/sdb

(parted) mklabel gpt
(parted) mkpart primary 0% 100%
(parted) quit

Verify that the partition was created is lsblk. 

Create the filesystem

mkfs.btrfs -f /dev/sdb1

Mount the filesystem

mkdir /mnt/ssd
mount /dev/sdb1 /mnt/ssd

Setup Auto-Mount

# lsblk -f /dev/sdb1
sdb1 btrfs efb9e1d6-ce13-4eae-94cf-0c1335539f1c 21T 0% /mnt/ssd

Now add the following list to /etc/fstab

UUID=efb9e1d6-ce13-4eae-94cf-0c1335539f1c /mnt/ssd btrfs defaults 0 0

This will auto-mount the UUID for /dev/sdb1 to /mnt/ssd