re: Mounting ext3fs/ext4fs
You cannot mount ext4fs. Usually you can mount ext3fs as ext2fs because ext3fs is ext2fs with some features like journalling tagged on. See
https://en.wikipedia.org/wiki/Ext3fs
This should do it:
# mount -o ro /dev/sd0i /mnt
If it does not please post what
fdisk reports:
# fdisk sd0