RHEL fails to start when moved to other LPAR

I had to move a RHEL server from one LPAR to another. The other LPAR is on a different physical server, but it is the same type/model.
LPAR boots from SAN. Boot disk is simply mapped to the new LPAR. FC adapter in the new LPAR is a different type.
I often do the same with AIX LPARs - without problems.

When I try to boot the new RHEL LPAR, it ends like shown below (complete output is attached).
I have searched for a solution, but without luck.
I hope someone here can point me in the right direction.

Regards, Carsten

[  199.222980] dracut-initqueue[319]: Warning: dracut-initqueue timeout - starting timeout scripts
[  199.740480] dracut-initqueue[319]: Warning: dracut-initqueue timeout - starting timeout scripts
[  199.741482] dracut-initqueue[319]: Warning: Could not boot.
[  199.745290] dracut-initqueue[319]: Warning: /dev/mapper/rhel-root does not exist
[  199.745607] dracut-initqueue[319]: Warning: /dev/rhel/root does not exist
[  199.745996] dracut-initqueue[319]: Warning: /dev/rhel/swap does not exist
         Starting Dracut Emergency Shell...
Warning: /dev/mapper/rhel-root does not exist
Warning: /dev/rhel/root does not exist
Warning: /dev/rhel/swap does not exist

Generating "/run/initramfs/rdsosreport.txt"


Entering emergency mode. Exit the shell to continue.
Type "journalctl" to view system logs.
You might want to save "/run/initramfs/rdsosreport.txt" to a USB stick or /boot
after mounting them and attach it to a bug report.


dracut:/#