[CentOS] CentOS LiveCD on USB

Tue Nov 19 16:55:22 UTC 2013
Glenn Eychaner <geychaner at mac.com>

I had already gotten rid of rghb. The grub2 entry on the key for booting the
LiveCD reads:

menuentry "CentOS 6.4 Live" {
set root=(hd0,1)
linux /CentOS-Live/isolinux/vmlinuz0 root=UUID=A352-6D7C ro liveimg nodiskmount nolvmmount selinux=disabled live_dir=/CentOS_Live/LiveOS
initrd /CentOS-Live/isolinux/initrd0.img

The contents of the LiveCD appear in /CentOS_Live as one would expect. The
boot fails right after a device scan (obvious by tens of lines listing "ataN:",
"scsiN:", "sd 0:0:0:0:", etc.) with the "No root device" error below.

In the rdshell, /dev/sda shows up as the internal system hard drive rather
than the USB key. The USB key does not show up as /dev/sdb nor any
other device that I can find. Finally, I looked in /dev/mapper (duh); it
contains /dev/mapper/control, but no /dev/mapper/live-rw.

Sorry for any confusion,

m.roth wrote:
> Glenn Eychaner wrote:
> > I have been following these instructions:
> > https://www.centos.org/forums/viewtopic.php?t=501
> > to put a bunch of utilities (Clonezilla, SystemRescue, CentOS
> > netinstall/rescue, etc.) on a single USB key.  It works great for
> everything (including
> > Ubuntu Live) except the CentOS 6.4 LiveCD. (You can see my postings at
> the bottom of
> > the forum.) When booting the LiveCD, I got:
> > 	Kernel panic - not syncing: Attempted to kill init!
> > 	Pid: 1, comm: init Not tainted 2.6.32-358.el6.i686 #1
> > After removing "quiet" and adding "selinux=disabled", I got more
> Get rid of rhgb, too.
> > information; the boot stalls after finding devices, and gives:
> > 	No root device "block:/dev/mapper/live-rw" found
> > dracut suggests adding "rdshell", which I did.  This was not helpful (I
> > had no idea what to do in the dracut shell), but did notice that in the
> dracut
> > shell /dev/ did NOT seem to contain my USB drive at /dev/sdb as I would
> expect.
> When you boot from a USB key, it always shows as /dev/sda. Second, rdshell
> is a grub shell.
> Are you trying to boot from the USB? If so, I'd fix the grub menu on that,
> if it's on /dev/sda1 of the flash drive, to use /dev/sda2 for the root=

Glenn Eychaner (geychaner at lco.cl)
Telescope Systems Programmer, Las Campanas Observatory