Comment # 1 on bug 1193330 from Fabian Vogt

Hm, not even a dracut emergency shell. The iscsi error appears to be a red
herring, I get that with successful boots as well.

Can you try with "rd.debug rd.shell rd.break=pre-mount" added to the kernel
cmdline and get the journal in the emergency shell? You should be able to write
it to the USB drive, assuming that it got detected.