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I want to install Ubuntu on an external USB hard drive (in a blank partition already made in mac) and then use rEFIt to alternate between operating systems.

The problem is that, when running the instalation program (Install Ubuntu 12.10) I am asked the next: "Device for boot loader instalation". And I get the next options:

  • /dev/sda ATA WDC WD3200AAJS-4 (320.1 GB) (Internal)
  • /dev/sda1
  • /dev/sdc WD 5000AAV External (500.1 GB) (External)
  • /dev/sdc1

What option should I select?

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up vote 0 down vote accepted

If you only have one partition on the external drive (the one you want for Ubuntu), then go with /dev/sdc WD 5000AAV External (500.1 GB) (External).

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Ok, i did so, but now, when I click Install a warning appears that says: No root file system is defined. Please correct this from the partitioning menu. What should I do now? – mcmacker4 Mar 3 '13 at 10:28
You need to have a partition with mount point "/". – ryebread761 Mar 5 '13 at 13:40

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