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I'm trying to boot Ubuntu from my USB drive. How do I know the drive name in Ubuntu since I haven't installed Ubuntu yet?

This guy is using /dev/sda1 for his USB drive. How did he figure that out?

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up vote 5 down vote accepted

When you boot Ubuntu from a Flash drive (where it is installed), it becomes the first USB device and is therefore named sda1.

If you install Ubuntu using the Ubuntu LiveCD opening options (use the install option instead of the one that says try LiveCD) to a flash drive you have plugged in before booting the CD, it will get correctly installed. When you boot from the USB later, it will show up the device as '/dev/sda'

Besides the Ubuntu reference in the comment,
here is a HowToGeek page for setting up a USB Installation from Windows.

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re: "where it is installed" - i have an installation image on my usb drive (ubuntu isn't actually "installed" yet). – lipton Sep 17 '09 at 14:12
@liption, By installation-image, i presume you are having a LiveCD ISO on the USB. That does not make it bootable. If you have used something like Unetbootin ( to setup your flash drive, it should boot correctly if you select that drive from your BIOS boot menu. – nik Sep 17 '09 at 14:32
Thanks. Followed your suggestion and got it working easily with LiveCD and Unetbootin. Awesome. – lipton Sep 17 '09 at 17:42

The reason a USB disk becomes /dev/sda1 is that USB-based storage devices, as well as eSATA devices are managed by the SCSI subsystem, instead of the IDE subsystem. This explains the S in SDA. The D stands for Disk, and the A letter is for the first disk. The second disk would be B, C, D, etc. Finally, the "1" at the end is for the partition number 1. There is also the /dev/sda device, which is the entire disk, as opposed to a single partition. You will uyse it for example to manage the partitioning of a disk. You will enter a command such as :

sudo fdisk /dev/sda

Have a nice day :-)


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+1 much better explanation of why the device is named so than the accepted answer. – quack quixote Oct 11 '09 at 7:50
With recent kernels (for a certain value of "recent"), libata is used and so both SCSI and IDE devices have sd at the beginning of the device name. – Ignacio Vazquez-Abrams Apr 13 '10 at 13:56

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