in the thread "boot from backup copy of fc5 on usb external disk?" i described my initial problems and final success Here I comment on the differences between kubuntu,fedora initrd I had success using two different kernel,initrd 1) obtained from a kubuntu install stanza in grub.conf: title FC5copy (2.6.15-26-386) usbfc5 /media/disk-1 (hd1,2)sdb3 rootusb root (hd1,2) ## sdb3 kernel /boot/vmlinuz-2.6.15-26-386 ro root=LABEL=rootusb rhgb quiet initrd /boot/initrd.img-2.6.15-26-386 This worked without any modifications on my part of the initrd init script Moreover the disks were _not_ reordered 2)using my mainfc5 stanza in grub.conf: title FC5copy (2.6.17-1.2174_FC5_usbrs4.sdb2sw.img) /media/disk-1 (hd1,2) root (hd1,2) ## sdb3 kernel /boot/vmlinuz-2.6.17-1.2174_FC5 ro root=LABEL=rootusb rhgb quiet initrd /boot/initrd_usbrs4.sdb2sw.img This also worked, but here I had to make modification of initrd init script both on "resume /dev/sdxx" and on "mkrootdev -t reiserfs -o defaults,ro /dev/sdc1" And here the disks _were_ reordered. usb originally sdc -> now sda first scsi originally sda now sdb second scsi originally sdb, now sdc This reordering caused me much confusion almost to the point where I was going to give up. So, the kubuntu kernel,initrd worked with minimum of fuss the fedora kernel,initrd rqrd days of effort, confusion (in part bc of my perpetual noobie status) Aside from the different results just noted my additional point here is that the initrd init files are almost completely different in the two cases. case 2) fedora initrd-2.6.17-1.2174_FC5 (modified toinitrd_usbrs4.sdb2sw.img) [root@bootp cleanrs3]# tail init mkblkdevs resume /dev/sdb2 echo Creating root device. mkrootdev -t reiserfs -o defaults,ro /dev/sdc1 echo Mounting root filesystem. mount /sysroot echo Setting up other filesystems. setuproot echo Switching to new root and running init. switchroot case 1) kubuntu: initrd.img-2.6.15-26-386 here the script is quite long; I will list the whole thing at the end. I am not competent enough to try and edit this init; as noted above, I didnt have to, it just worked. This init has none of the fedora init structure no use at all of mkrootdev, sysroot, switchroot googling "could not find /dev/root" gives a lot of msgs over the past few years, all failing sysroot, switchroot, and ending in kernel panic, mostly from redhat,fedora users. I dont think I saw even one from ubuntu users-- that now is no surprise bc the ubuntu init file does its thing in a different way. Here is the init file from initrd.img-2.6.15-26-386 I would be interested in comments as to what it is doing; and especially if anyone knows how it avoids reordering the disks. [root@bootp clean386]# cat init #!/bin/sh mkdir /sys mkdir /proc mkdir /tmp mkdir -p /var/lock mount -t sysfs none /sys mount -t proc none /proc # Note that this only becomes /dev on the real filesystem if udev's scripts # are used; which they will be, but it's worth pointing out mount -t tmpfs -o mode=0755 udev /dev touch /dev/.initramfs-tools mkdir /dev/.initramfs mknod /dev/console c 5 1 mknod /dev/null c 1 3 # Export the dpkg architecture export DPKG_ARCH= . /conf/arch.conf # Bring in the main config . /conf/initramfs.conf for i in conf/conf.d/*; do [ -f ${i} ] && . ${i} done . /scripts/functions # Parse command line options export break= export init=/sbin/init export quiet=n export readonly=y export ROOT= export resume=${RESUME} export rootmnt=/root export debug= for x in $(cat /proc/cmdline); do case $x in init=*) init=${x#init=} ;; root=*) ROOT=${x#root=} case $ROOT in LABEL=*) ROOT="/dev/disk/by-label/${ROOT#LABEL=}" ;; UUID=*) ROOT="/dev/disk/by-uuid/${ROOT#UUID=}" ;; esac ;; nfsroot=*) NFSROOT=${x#nfsroot=} ;; boot=*) BOOT=${x#boot=} ;; resume=*) resume=${x#resume=} ;; quiet) quiet=y ;; ro) readonly=y ;; rw) readonly=n ;; debug) debug=y exec >/tmp/initramfs.debug 2>&1 set -x ;; break=*) break=${x#break=} ;; break) break=premount ;; esac done depmod -a maybe_break top # Don't do log messages here to avoid confusing usplash run_scripts /scripts/init-top . /scripts/${BOOT} parse_numeric ${ROOT} maybe_break modules log_begin_msg "Loading essential drivers..." load_modules log_end_msg maybe_break premount [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/init-premount" run_scripts /scripts/init-premount [ "$quiet" != "y" ] && log_end_msg maybe_break mount log_begin_msg "Mounting root file system..." mountroot log_end_msg maybe_break bottom [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/init-bottom" run_scripts /scripts/init-bottom [ "$quiet" != "y" ] && log_end_msg # Move virtual filesystems over to the real filesystem mount -n -o move /sys ${rootmnt}/sys mount -n -o move /proc ${rootmnt}/proc while [ ! -x ${rootmnt}${init} ]; do panic "Target filesystem doesn't have ${init}" done maybe_break init # Unset the problematic debug variable and chain to real filesystem unset debug exec run-init ${rootmnt} ${init} "$@" <${rootmnt}/dev/console >${rootmnt}/dev/console [root@bootp clean386]# regards, Jack