External USB Drives in Linux
18 Feb 2023
Many modern Linux distros will auto-mount USB drives - they just pop up in the graphical file manager as users would expect. When you’re running server, older, or smaller versions, that’s probably not going to be the case, and you’ll have to do it old school.
Let’s look at some basics. [lsblk](https://man7.org/linux/man-pages/man8/lsblk.8.html) will list the ‘block’ devices. Your output will almost certainly be a bit different than this.
root@pve:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 119.2G 0 disk
├─sda1 8:1 0 1007K 0 part
├─sda2 8:2 0 512M 0 part /boot/efi
└─sda3 8:3 0 118.7G 0 part
├─pve-swap 253:0 0 7.7G 0 lvm [SWAP]
├─pve-root 253:1 0 39.8G 0 lvm /
├─pve-data_tmeta 253:2 0 1G 0 lvm
│ └─pve-data-tpool 253:4 0 54.6G 0 lvm
│ ├─pve-data 253:5 0 54.6G 1 lvm
│ ├─pve-vm--100--disk--0 253:6 0 10G 0 lvm
│ ├─pve-vm--101--disk--0 253:7 0 10G 0 lvm
│ ├─pve-vm--300--disk--0 253:8 0 8G 0 lvm
│ ├─pve-vm--102--disk--0 253:9 0 4M 0 lvm
│ └─pve-vm--102--disk--1 253:10 0 32G 0 lvm
└─pve-data_tdata 253:3 0 54.6G 0 lvm
└─pve-data-tpool 253:4 0 54.6G 0 lvm
├─pve-data 253:5 0 54.6G 1 lvm
├─pve-vm--100--disk--0 253:6 0 10G 0 lvm
├─pve-vm--101--disk--0 253:7 0 10G 0 lvm
├─pve-vm--300--disk--0 253:8 0 8G 0 lvm
├─pve-vm--102--disk--0 253:9 0 4M 0 lvm
└─pve-vm--102--disk--1 253:10 0 32G 0 lvm
If you look at the type column, you can see this machine has one disk, with three partitions, and the last partition has a heap of logical volumes. Let’s plug the thumb drive in:
root@pve:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 119.2G 0 disk
├─sda1 8:1 0 1007K 0 part
├─sda2 8:2 0 512M 0 part /boot/efi
└─sda3 8:3 0 118.7G 0 part
├─pve-swap 253:0 0 7.7G 0 lvm [SWAP]
├─pve-root 253:1 0 39.8G 0 lvm /
├─pve-data_tmeta 253:2 0 1G 0 lvm
│ └─pve-data-tpool 253:4 0 54.6G 0 lvm
│ ├─pve-data 253:5 0 54.6G 1 lvm
│ ├─pve-vm--100--disk--0 253:6 0 10G 0 lvm
│ ├─pve-vm--101--disk--0 253:7 0 10G 0 lvm
│ ├─pve-vm--300--disk--0 253:8 0 8G 0 lvm
│ ├─pve-vm--102--disk--0 253:9 0 4M 0 lvm
│ └─pve-vm--102--disk--1 253:10 0 32G 0 lvm
└─pve-data_tdata 253:3 0 54.6G 0 lvm
└─pve-data-tpool 253:4 0 54.6G 0 lvm
├─pve-data 253:5 0 54.6G 1 lvm
├─pve-vm--100--disk--0 253:6 0 10G 0 lvm
├─pve-vm--101--disk--0 253:7 0 10G 0 lvm
├─pve-vm--300--disk--0 253:8 0 8G 0 lvm
├─pve-vm--102--disk--0 253:9 0 4M 0 lvm
└─pve-vm--102--disk--1 253:10 0 32G 0 lvm
sdb 8:16 1 14.5G 0 disk
└─sdb1 8:17 1 14.5G 0 part
There we are, down the bottom. Our disk is sdb, and partition is sdb1. So the OS knows it exists - it’s recognised, but to use it we need to mount it to the file system somewhere. Mounting it will let us see and interact with the files on the drive.
By convention, removable media is often mounted in /media or /mnt, but it can be wherever you like. Let’s make a directory for it in /media and mount it there.
root@pve:/# mkdir /media/external
root@pve:/# mount /dev/sdb1 /media/external
root@pve:/# ls /media/external
'02 Advance Australia Fair 1 verse vocal.mp3' 'Year 3 Pack.pdf'
'Araw ng Kasarinl'$'\341''n.mp4' 'Year 4 Pack.pdf'
'System Volume Information' 'Year 5 Pack.pdf'
'Year 1 Pack.pdf' 'Year 6 Pack.pdf'
'Year 2 Pack.pdf'
root@pve:/#
Success!
If we do the lsblk again, you’ll see out mount point in the listing
root@pve:/# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 119.2G 0 disk
├─sda1 8:1 0 1007K 0 part
├─sda2 8:2 0 512M 0 part /boot/efi
└─sda3 8:3 0 118.7G 0 part
...
sdb 8:16 1 14.5G 0 disk
└─sdb1 8:17 1 14.5G 0 part /media/external
Of course, just as in Windows, we need to tell the OS when we want to remove a removable drive to ensure that any caches are flushed and that we don’t inadvertently lose data when we yank it out. This is the unmounting process.
We can unmount a drive with the [umount](https://man7.org/linux/man-pages/man8/umount.8.html) command.
root@pve:/# ls /media/external
'02 Advance Australia Fair 1 verse vocal.mp3' 'Year 3 Pack.pdf'
'Araw ng Kasarinl'$'\341''n.mp4' 'Year 4 Pack.pdf'
'System Volume Information' 'Year 5 Pack.pdf'
'Year 1 Pack.pdf' 'Year 6 Pack.pdf'
'Year 2 Pack.pdf'
root@pve:/# umount /media/external
root@pve:/# ls /media/external
root@pve:/#