Convert ext3 root to jfs

Question

Hello all,
I would like to convert my root file system from ext3 to jfs. I made a first unsuccessful attempt. This is what I did:
- Booted my laptop with systemrescue cd and mounted my root partition (/dev/sda3).
- Copied all data from it to another partition using cp -a (except /proc and /sys).
- Unmounted the root partition.
- Created a jfs file system on it using 'mkfs.jfs /dev/sda3'.
- Mounted the root partition.
- Copied back all files to it using cp -a.
- Created empty /proc and /sys directories.
- Edited the /etc/fstab file and changed ext3 to jfs for the root file system.
- Unmounted the root partition again.
- Rebooted.
The laptop boots, but fails to mount the file system. It says the partition is of type jfs, but then I get:
kinit: Cannot open root device sda3(8,3)
kinit: init not found
Kernel panic - not syncing: Attempted to kill init!
Can anyone see what I did do wrong? My boot partition is ext2.
Regards,
Kimmo

Answer 1

Well, proc and sys would have been empty anyways, so it would have been OK to copy them, would have saved some steps, but that is not really relevant.
Did you try the rescue (fallback) ramdisk? JFS is not built into the kernel. As far as that goes, I don't think any FS is is built into the kernel. You may need to rebuild the initrd, if you can boot with the rescue one.
Hmmm... Init not found. That makes me think the directory structure did not get replicated identically.
The procedure should have gone something like this (replace old, spare, new as need be)
# boot rescue CD and get a root prompt
mkdir /mnt/old
mkdir /mnt/new
mkdir /mnt/spare
mount /dev/sda3 /mnt/old
mount /dev/spare /mnt/spare
cp -a /mnt/old/* /mnt/spare/
umount /mnt/old
mkfs.jfs /dev/sda3
mount /dev/sda3 /mnt/new/
cp -a /mnt/spare/* /mnt/new/
umount /mnt/spare
umount /mnt/new