RON

The only thing coming to my mind then is to
“grub-install /dev/sdb” (install HDD bootloader)
Then
“mount /dev/sdb1 /mnt” (mount the root partition into mnt)
And then edit /mnt/boot/grub/menu-1st by replacing all the sdb entries with sda (actually you should see “hd0″ entries IIRC).

If you’re very limited, you can also perform
“chroot /mnt” after mounting the drive.

Yup, a very “automatic” solution

Thanks for the udev tip, I didnt know about renaming devices. However that’s not the whole solution, since the problem starts before the OS is loaded – the bootloader still sees the disks as different numbers depending on whether the USB stick is plugged in or not. This is solvable once you’ve got the OS installed, but the trouble is if you use any bootable recovery tools like Super Grub Disk and such, they never do the right thing by default because the numbering is never the same when booting with/without the USB stick plugged in. I discovered this when I tried to use Super Grub Disk to fix the problem, but ended up having to do everything very manually.

Since I rarely have to touch the server once it’s installed, I like to keep things as simple as possible, and the last thing I want is complications if I have to do an emergency restore or fix. So I’ve put an old DVD drive in there and it’s made things much simpler. I also found that not all ISOs were useful through UNetbootin – the Ubuntu Server ISO for example doesn’t work because it insists on looking for a CD device, despite the fact that the same media is on the USB disk it booted the installer from.

So, it was a nice idea, but in the end too much of a pain.

If I get your problem correctly, you installed from the USB, rebooted with the SATA disk, but it doesn’t boot because GRUB looks for /dev/sda and your disk is in /dev/sdb ?
If that’s the problem, rename the device from /dev/sdb to sda and you’ll be fine, udev should be saved for the next season.

Alternatively you can try “grub-install /dev/sdb” which should work (fastest solution).

Again, I’m not 100% sure what your problem is. Could you add some more details? Thanks

In order to get the USB booting, I had to set it to the top of the priority, which seems to make it get the lowest SCSI ID. That means that it always grabs /dev/sda. Because I’m using SATA disks, they get shunted to /dev/sdb onwards. This confuses the GRUB setup which then doesn’t work when you reboot without the USB stick installed. Of course, you can manually tweak the setup, but the fact that you can only do that by booting from the USB, where the devices are not correctly numbered, it makes it far more hassle than it’s worth.

Maybe there’s a way of making a bootable USB come up as the last SCSI ID instead of the first (thus not messing with the device names), but I couldn’t find it.

@irrdev – that’s fine so long as you have a running version of Ubuntu already. Sure, you can create it from the LiveCD, but that assumes you have a CD drive (I know, you could use another machine, but it’s the principle of the thing). UNetbootin is the only 1-stop way. Plus, it can create bootable installs from server ISOs rather than just the desktop version.

Note: The USB Startup Disk Creator has only been included by default since Ubuntu Intrepid, although I believe it has been back-ported to Hardy.

The only real use I’ve given floppy drives in today’s computers is when I have to perform a memtest because the system is failing.

Formating a bootable USB (with memtest+) is absurdly hard (though it can be done, and this include SD cards), and it’s overkill to use a blank CD/DVD either for a couple of MBs