Pi USB disk

Have an old laptop?
Reuse it’s disk as a USB drive for your Pi.

Assumes that the old drive is SATA (most relatively modern laptops will be).

You will need a USB to SATA adapter cable, such as this one.

Run lsblk to identify the disk and any partitions that currently exist.
In this example the disk is sdb and has 4 partitions - it came from an old HP laptop that was no longer capable of running Windows.

root@pib:~# lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 111.8G  0 disk
├─sda1   8:1    0    94M  0 part /boot
└─sda2   8:2    0 111.7G  0 part /
sdb      8:16   0 298.1G  0 disk
├─sdb1   8:17   0   300M  0 part
├─sdb2   8:18   0 277.6G  0 part
├─sdb3   8:19   0  15.2G  0 part
└─sdb4   8:20   0     5G  0 part

Use parted to remove exiting partitions (rm) and create a new one (mkpart) using the whole disk.

root@pib:~# parted /dev/sdb
GNU Parted 3.2
Using /dev/sdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print
Model: Hitachi HTS723232A7A364 (scsi)
Disk /dev/sdb: 320GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number  Start   End    Size    Type     File system  Flags
 1      1049kB  316MB  315MB   primary  ntfs         boot
 2      316MB   298GB  298GB   primary  ntfs
 3      298GB   315GB  16.4GB  primary  ntfs
 4      315GB   320GB  5363MB  primary  fat32        lba

(parted) rm 4
(parted) rm 3
(parted) rm 2
(parted) rm 1
(parted) print
Model: Hitachi HTS723232A7A364 (scsi)
Disk /dev/sdb: 320GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number  Start  End  Size  Type  File system  Flags

(parted) mkpart primary ext4 0% 100%
(parted) print
Model: Hitachi HTS723232A7A364 (scsi)
Disk /dev/sdb: 320GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number  Start   End    Size   Type     File system  Flags
 1      1049kB  320GB  320GB  primary  ext4         lba

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

Format the new partition and mount it.
If the disk came from a laptop that was running Windows you will probably see the warning about SYSTEM filesystem.

root@pib:~# lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 111.8G  0 disk
├─sda1   8:1    0    94M  0 part /boot
└─sda2   8:2    0 111.7G  0 part /
sdb      8:16   0 298.1G  0 disk
└─sdb1   8:17   0 298.1G  0 part

root@pib:~# mkfs.ext4 /dev/sdb1
mke2fs 1.43.4 (31-Jan-2017)
/dev/sdb1 contains a ntfs file system labelled 'SYSTEM'
Proceed anyway? (y,N) y
Creating filesystem with 78142464 4k blocks and 19537920 inodes
Filesystem UUID: 3ce5b730-fc17-4114-86e0-d43fdc0755fe
Superblock backups stored on blocks:
	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
	4096000, 7962624, 11239424, 20480000, 23887872, 71663616

Allocating group tables: done
Writing inode tables: done
Creating journal (262144 blocks):
done
Writing superblocks and filesystem accounting information: done

root@pib:~# mkdir -p /disk/sdb
root@pib:~# mount /dev/sdb1 /disk/sdb
root@pib:~# df -k /disk/sdb
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/sdb1      306615224   65564 290904784   1% /disk/sdb

Get the partition UUID and add entry to fstab (if you want disk to mount when Pi boots).

root@pib:~# blkid -o export
...
DEVNAME=/dev/sdb1
UUID=3ce5b730-fc17-4114-86e0-d43fdc0755fe
TYPE=ext4
PARTUUID=ad98c14a-01

## example fstab entry
PARTUUID=ad98c14a-01 /disk/sdb        ext4    defaults,noatime  0       1