On Tue,  3 Apr 2018 00:13:48 +0200 (CEST), Nomen Nescio
 wrote:

> Bernd  wrote:
>
>> I think that in the file /boot/cmdline.txt I can do the trick.
>
> root=/dev/sdb1

yes, or

root=PARTUUID=4d7e5657-02

You can find the PARTUUID with
lsblk -O


My /boot/cmdline.txt:

dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1
root=PARTUUID=4d7e5657-02 rootfstype=ext4 elevator=deadline
fsck.repair=yes rootwait

(note: the above is in one line, wrapped for usenet etiquette)
--
Regards,
Kees Nuyt

--- SoupGate-Win32 v1.05