I started off following the ubuntu guide for installing a new drive, which uses fdsik to create the partitions how ever after formatting and mounting I ran df -h:

Filesystem      Size  Used Avail Use% Mounted on
/dev/sdb1       2.0T   28G  1.9T   2% /mnt/kryten/disk5

Which is not 3TB

I then found this article which worked in the long run not sure if I typo’d a command but similar to this other user I had to run through the commands a second time for them to work.

To start with use parted instead of fdisk, this allows the gpt partition table that fdisk does not.

(parted) mklabel gpt 
Warning: The existing disk label on /dev/sdb will be destroyed and all data on
this disk will be lost. Do you want to continue?
Yes/No? yes    
(parted) unit TB 
(parted) mkpart primary 0.00TB 3.00TB                                     
Warning: You requested a partition from 0.00TB to 3.00TB.                 
The closest location we can manage is 0.00TB to 0.00TB.
Is this still acceptable to you?
Yes/No? yes

basically after this point it showed up as a few KB after formatting, tried it again and it seemed to work much better.

(parted) mklabel gpt                                                       
Warning: The existing disk label on /dev/sdb will be destroyed and all data on
this disk will be lost. Do you want to continue?
Yes/No? yes                                                               
(parted) unit TB                                                          
(parted) mkpart primary 0.00TB 3.00TB                                     
(parted) print                                                            
odel: Unknown (unknown)
Disk /dev/sdb1: 3001GB
Sector size (logical/physical): 512B/4096B
Partition Table: loop

Number  Start   End     Size    File system  Name     Flags
1      0.00TB  3.00TB  3.00TB               primary

(parted) quit                                                             
Information: You may need to update /etc/fstab.

Format

$ sudo mkfs.ext4 /dev/sdb1
$sudo parted /dev/sdb1
(parted) print
Model: Unknown (unknown)
Disk /dev/sdb1: 3001GB 
Sector size (logical/physical): 512B/4096B
Partition Table: loop

Number  Start  End     Size    File system  Flags
1      0.00B  3001GB  3001GB  ext4

Reduce Reserved Space

By default 5% is reserved for the root to stop the driving becoming unusable when full, for data and not the main OS drive this does not matter too much, and 5% was decided when drives where much small. 5% of 3TB is 150 GB, way too much. Turn this down to 1% with:

sudo tune2fs -m 1 /dev/sdb1

Mount

sudo mkdir /mnt/kryten/disk5 
sudo mount /dev/sdb1 /mnt/kryten/disk5

Find UUID

$ sudo blkid
/dev/sda1: UUID="c41cba49-bd3a-41d7-961c-b4ad45d48ed1" TYPE="ext4" 
/dev/sdb1: UUID="d822c6af-9802-4d00-8de8-61f1653a854a" TYPE="ext4" 
/dev/sdc1: UUID="59a61ceb-fee3-460a-97c5-e9f115776daf" TYPE="ext4" 
/dev/sdc5: UUID="80f9c384-9a5a-4563-921a-5c25628e1b2e" TYPE="swap"

Update /etc/fstab

$sudo vim /etc/fstab

#/dev/sdb1 3TB drive replacing 1.5TB old UUID Below
UUID=d822c6af-9802-4d00-8de8-61f1653a854a     /mnt/kryten/disk4 ext4 rw,auto,user,exec,async,errors=remount-ro 0 1
#UUID=c41cba49-bd3a-41d7-961c-b4ad45d48ed1    /mnt/kryten/disk4 ext4 rw,auto,user,exec,async,errors=remount-ro 0 1