Running 10.04 on non-bootable esata hard drive?

[slawek_zachcial]

Hello,

I have a laptop (hp 8530w) with Vista and disk encryption software installed on the internal hard drive. As I cannot touch the internal hard drive, I would like to install and run Ubuntu from an external hard drive (500 hitachi in an enclosure with USB and eSata port). The idea being that when the drive is connected I run Ubuntu and when it is not the internal HDD is used to boot.

I already installed Ubuntu 10.04 LTS on this external hard drive. I would like to run it using eSata interface and not USB as the former offers better performance.

Unfortunately, as it turns out my BIOS does not allow me to boot directly from eSata disk. I can however boot from USB.

I thought it would be possible to install a boot loader on a USB stick and tell it somehow that Ubuntu is installed on the eSata disk and load the system from there.
I installed GRUB on a USB stick without grub.cfg. This allowed me to load GRUB and get to its shell. Here I discovered another issue. Using GRUB "ls" command the eSata drive is not listed - I can see the USB stick (hd0) and the internal drive (hd1) but no eSata drive.

Not being an expert I don't know when in the boot process the eSata disk is detected. If I load Ubuntu completely from USB stick I can see it listed with "fdisk -l" command.

At this point, knowing that I can boot from USB, I'm wondering if there is any way to have a hybrid solution with USB stick storing only what's required to bootstrap Ubuntu, and then have everything else stored on and mounted to my external drive.


Does anyone know how to do that?

Is there any other, better way (assuming I cannot do anything on the internal hard drive like repartitioning it, etc ...) to get to what I'm after?


I know that I could boot and run Ubuntu using USB interface only but as I stated above I would like to use eSata as it offers better performance.

I suppose I'm not the only one trying to do that. Unfortunately my web research did not reveal any solutions. Any help would be greatly appreciated.

Thanks,
/Slawek

[slawek_zachcial]

It seems the solution may be to use "kexec-loader" (http://www.solemnwarning.net/kexec-loader/) which, based on its description, was designed for exactly what I'm trying to do.

Does anyone have any experience with "kexec-loader"?

I'm not giving up yet...

/Slawek

[slawek_zachcial]

With great help from Daniel Collins, the creator of "kexec-loader", I'm now able to boot from USB key into Ubuntu installed on external hard drive connected with eSata.

Below are the steps I followed to get there. It may not be the simplest way but it worked for me.

IMPORTANT: If you decide to follow the steps below always make sure that you work on the right disk (i.e. external) to not wipe out the data from your internal drive. Also doing a backup of your internal disk is a good idea in case things don’t go as expected.

0. Prerequisites

- Ubuntu on Live USB stick with some presistent storage
- Small USB key which will be used for booting
- External hard drive connected though eSata

1. Ubuntu installation on external disk

This is done using Live USB. Go through the installation steps until you reach the screen about partitioning. Here I had to used the “advanced” option (the radio button at the very bottom) as none of the others seemed to be able to work with the external disk. Once you get to the next screen it should show partitions on the internal disk but also on the external disk. Let’s say my external disk is “/dev/sdb”.

Here I selected my external disk and created 2 primary partitions: swap - with 2x the size of RAM in my laptop, ext4 - using the remaining space and mounted to “/”.

Go to through the following screen(s) until you reach the summary with “Advanced” button. Hit this button and uncheck the box about updating the boot record - I didn’t want to do it as my BIOS does not support eSata booting anyway (otherwise I would specify it should boot from my external disk, i.e. /dev/sdb instead of /dev/sda).

Review the changes to make sure that any disk changes will only be done on the external drive. And then GO - Ubuntu should be installed in your external drive.

2. “kexec-loader” ISO preparation

While running Ubuntu from the Live USB key go to http://www.solemnwarning.net/kexec-loader/download.cgi and download from there kexec-loader-2.2.1-cdrom.tar.gz and modules-2.6.30.5-1.tar.gz.

Unpack both of them. From the modules copy “sata.tlz” and “ext4.tlz” into “kexec-loader-2.2.1-cdrom/iso-modules” directory. Note that if you used another file system than “ext4” to install Ubuntu you should take the appropriate module for your installation.

In kexec-loader-2.2.1-cdrom run “mkiso.sh kexecloader.iso”. This will create ISO image that we will use for boot.

3. Bootable USB preparation

Plug the 2nd USB key that we will use for boot. With GParted format it to FAT32 and label the partition as KEXECLOADER. The label is important as “kexec-loader” during boot will look for a partition with that name to read its configuration file from there.

Get access to the files in the created ISO image using the following commands:
$ mkdir /mnt/kexecloadercd
$ mount -o loop path/to/iso /mnt/kexecloadercd

Download UNetBootin tool used to create bootable USB. If you run plain Ubuntu, it will complain about missing “p7zip-full”. I don’t know if this is really needed but I installed it following one of the “to do list after installing Ubuntu 10.04” posts.

Run UNetBootin. Select “Custom”. In “Kernel” open the one in /mnt/kexecloadercd/isolinux/vmlinuz. In “Initrd” open the one in /mnt/kexecloadercd/isolinux/initrd.img. In the USB dropdown make sure you select the one that we just formated above and that will be used for boot. In my case it was visible as “/dev/sdd” device. Hit OK.

If used as-is the UNetBootin USB stick will show a menu at start up. If you want to avoid that backup “syslinux.cfg” present there and replace it with one containing just this line:

default /ubnkern initrd=/ubninit

4. “kexec-loader.conf” configuration file

The final step is to tell kexec-loader about the external disk Ubuntu is installed on.

In the root directory of the USB boot disk create file called “kexec-loader.conf” with the following content:

timeout 5
title Lucid Lynx on eSata
root sdb3
kernel /vmlinuz
cmdline root=/dev/sdb3
initrd /initrd.img

... and replace “sdb3” with the device name for the partition of your external disk where Ubuntu is installed.

Alternatively, you can use UUID instead of “sdbN”. To get UUID execute in terminal “ls -l /dev/disk/by-uuid” and then in “kexec-loader.conf” file use:
...
root UUID=<your uuid>
...
cmdline root=UUID=<your uuid>
...

(“=” is present twice in cmdline)

Note that “kexec-loader” has a shell that you can use for troubleshooting. Its commands are documented at http://www.solemnwarning.net/kexec-loader/readme.html in “Shell” and “Shell Reference” sections.

5. BIOS boot order

If you want to automatically boot from your USB key when it’s plugged in you’ll need to change the boot order in BIOS and put the USB hard drive above internal hard drive.

Doing all the above I’m now able to boot into Ubuntu installed on my external drive when my USB stick is plugged in, and into my internal drive when the boot stick is not connected.

Hope others will find this useful. Enjoy!

/Slawek

[frostschutz]

there's no need for a kexec-loader really, all you have to do is install grub on the usb stick, and put your /boot partition and kernels on the usb stick as well.

when you boot from usb, grub can then load the kernel normally (from hd0 == usb), detect your devices, mount the root partition (from /dev/sdx == esata), and start the system init process...

[slawek_zachcial]

What you describe is somewhat close to what I wanted to do (see my initial post). Unfortunately I haven't found any documentation or posts about such a setup and I decided to try kexec-loader which worked pretty well for me.

Where can I find more information about the setup you highlight?

Thanks,
/S