I can't tell which dev/sda/ file is my external hard drive to install Xubuntu on

Question

I want to install Xubuntu onto my external hard drive, but I cannot tell what partition to use. Here is what it shows

dev/sda
dev/sda1 ntfs
dev/sda2 ntfs
dev/sda3 ntfs
dev/sda4 fat32

sda1-3 are Windows 8 files, but I don't know what the last one is, however I think it might be the hard drive, but I don't want to erase anything.

Solution 1

The disk names in Linux are alphabetical. /dev/sda is the first hard drive (the primary master), /dev/sdb is the second etc. The numbers refer to partitions, so /dev/sda1 is the first partition of the first drive.

It is likely that your external drive will not be /dev/sda, that is more likely to be the internal drive of your machine. To find out the name of your (attached) USB drive, run sudo fdisk -l.

Example output:

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x4b66b5d5

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1              63       80324       40131   de  Dell Utility
/dev/sda2   *       81920    30801919    15360000    7  HPFS/NTFS/exFAT
/dev/sda3        30801920   194643539    81920810    7  HPFS/NTFS/exFAT
/dev/sda4       194643601   976773119   391064759+   f  W95 Ext'd (LBA)
/dev/sda5       194643603   198836504     2096451    c  W95 FAT32 (LBA)
/dev/sda6       342951936   960387071   308717568   83  Linux
/dev/sda7       198840320   342949887    72054784   83  Linux
/dev/sda8       960389120   976773119     8192000   82  Linux swap / Solaris

Partition table entries are not in disk order

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x484882da

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1              63   976768064   488384001    7  HPFS/NTFS/exFAT

That command will list all partitions of all connected drives, it will probably include some /dev/sdbX partitions as well and those are the ones you want. In the output above, my external USB drive is sdb and has the partition sdb1.

You can also see the device name of your USB drive with lsblk:

$ lsblk 
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 465.8G  0 disk 
├─sda1   8:1    0  39.2M  0 part 
├─sda2   8:2    0  14.7G  0 part 
├─sda3   8:3    0  78.1G  0 part /winblows
├─sda4   8:4    0     1K  0 part 
├─sda5   8:5    0     2G  0 part 
├─sda6   8:6    0 294.4G  0 part /home
├─sda7   8:7    0  68.7G  0 part /
└─sda8   8:8    0   7.8G  0 part [SWAP]
sdb      8:16   0 465.8G  0 disk 
└─sdb1   8:17   0 465.8G  0 part 
sr0     11:0    1  1024M  0 rom  

Again, in the example above, sdb is my external USB drive.

Solution 2

/dev/sda it's 100% your internal drive. Your external drive may be sdb, sdc or another one.

To list your drives try: sudo parted -l to list all drives and information about them.

Solution 3

Run udevadm monitor and plug in your drive. This will tell you where your drive is at in the dev directory.

For example, one of the output lines from plugging in a USB drive on my PC (partition ID in bold):

KERNEL[90052.302744] add      /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.3/2-1.3:1.0/host6/target6:0:0/6:0:0:0/block/sdd/sdd1 (block)

Comments

[Garrett]

My external USB drive is indeed /dev/sda. The internal drive of my machine is /dev/nvme0n1.

[Devon]

Same here. It is possible for secondary and external hard drives to be named sda

[terdon]

Yes, these are probably laptops with internal nvme SSD drives. Those weren't very common when this answer was written, they have become much more common now.