Boot USB stick from GRUB on hard disk? [WORKED-AROUND]

Havin_it · Last edited by Havin_it on Mon Oct 09, 2006 10:37 am; edited 1 time in total

Hi all,

I always thought my laptop was able to boot off USB devices, but it now looks like it can't.

I'm still interested in using some LiveUSB stuff, and I'm wondering: Is it possible to boot the stick from within the hard-drive-installed GRUB? If so, will the LiveUSB contents need to be modified at all?

Thanks in advance

NeddySeagoon · Posted: Fri Oct 06, 2006 8:46 pm Post subject:

Havin_it,

I think it depends on what you have on the hard drive.
Grub alone - it may be difficult, since the BIOS would need to show the USB stick to grub.
Grub and kernel, then mount root and everything else from the USB stick ?
That should be fairly easy.
Your kernel will need all the USB bits and pieces built in, including USB-Storage and SCSI disk.
You will ned an extra kernel line parameter in grub .... rootdelay=<secs> <secs> in the range 7..30 is reported to be good. This allows the USB subsystem to initialise before you attempt to use it to mount root.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Havin_it · Posted: Sun Oct 08, 2006 12:24 pm Post subject:

Hi NeddySeagoon, thanks for clearing that up. I guess this means I am defeated then, as what I was hoping for was just a GRUB option to say: "Boot whatever kernel is on the USB". But when I think about it, obviously that won't work if the BIOS can't see it in the first place. Oh well...

I'll tell you why I was asking: I need to resize my root partition, and found that I need GParted for this (well, that or some command-line futzing that scared the bejaysus off me). And being a typical Scot tightwad, I don't want to waste a whole CD on a 30MB LiveCD that only does one thing. (Yes, I suppose I could hunt down a full-featured LiveCD that includes GParted, but I got too many of them too...) So I was hoping to use their LiveUSB distro instead.

Alternative scheme: If I place the LiveUSB contents into my /boot partition and point GRUB at the correct thing, could I boot it from there and use it to operate on the / partition?

NeddySeagoon · Posted: Sun Oct 08, 2006 1:14 pm Post subject:

Havin_it,

Lets look at this problem from another angle. You need more space for root.
There are several ways around this. Resizing the partion is only one.

Another, lower risk one is to move things off of root.
/home, /var, /usr and /tmp are all candidates.
You move the contents of one of these directories onto another partition, delete the orignal files and mount the extra partition using the old directory name as a mount point.

You can also remove the contents of /usr/portage/distfiles - thats all the sources you have ever downloaded.

I reccomend you do not try resizing partitons withou a full validated backup. It might not work.
Not all file systems can be resized either.

I know a little about the Scots. Put my location in Google, if you don't know where it is.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Havin_it · Posted: Mon Oct 09, 2006 12:28 am Post subject:

Valid suggestions, but I tend against partitioning any more extensively than I can avoid. I prefer keeping my options open, so more parts of the filesystem can grow/shrink as needed. I only really have multiple partitions at all because I'm dual-booting with Windows. My full map is like this (in actual order on disk):

hda2 : /boot (Ext2, 55MB)
hda1 : /win_c (NTFS, ~14GB)
hda3 : / (Ext3, ~10GB)
hda5 : SWAP, 768MB
hda6 : /win_d (FAT32, ~4GB)

Everything valuable gets rsync'd to my trusty server box regularly, so no worries there. Basically, after my last reinstall of Windurrrrz I decided - since I've been using it less and less - to shrink it a bit and give the rest to Linux. I got as far as the shrinking part with QTParted on a Knoppix disc, then spent nearly an hour wondering why it wouldn't let me then move and expand the / partition. :oops:

The teeny /boot partition, which normally I keep unmounted, is bigger than it needs to be for holding GRUB plus two kernels, but it has just enough space left to squeeze-in the Gparted LiveCD/USB, if I can make it work. Expediency, don'tcher know...?

According to Google Maps, you live on the Rosyth-Zeebrugge Superfast Ferry! AICMFP :wink:

Havin_it · Posted: Mon Oct 09, 2006 10:36 am Post subject:

Yaaaaahhhh - got a result, after a bit of foraging in the GParted forums.

I extracted the contents of the LiveCD iso to /boot, and added the following entry to menu.lst:

NeddySeagoon · Posted: Mon Oct 09, 2006 11:16 am Post subject:

Havin_it,

Hmm - I'm glad it worked. I'm not a fan of everything in a single partiton and changing sizes on the drive like that.
If you ever do another install, have a look at Logical Volume Manager, LVM2 now.
It provides another layer of hard drive abstraction, so you can move space around 'on the fly'.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Gentree · Posted: Mon Oct 09, 2006 11:54 am Post subject:

Havin_it · Posted: Tue Oct 10, 2006 12:04 am Post subject:

Gentree · Posted: Tue Oct 10, 2006 12:21 am Post subject:

my root is 7.8GB and takes about 10m to clone once I've booted to another medium. rsync sounds good if you permnenlty hooked up to another machine.

Mine's basically a stand alone, one disk box, that's why I liked your gparted in /boot idea, so seriously, how much space did it need?

Thx.
_________________
Linux, because I'd rather own a free OS than steal one that's not worth paying for.
Gentoo because I'm a masochist
AthlonXP-M on A7N8X. Portage ~x86

Havin_it · Posted: Tue Oct 10, 2006 12:40 am Post subject:

Seriously? The ISO is 28.5MB, the LiveUSB once extracted is 28.2MB.