thanks, i retained now as 82 - Linux Swap.
At another test making a raid1 i had again my initial problem. System was not booting from md2, it still uses sda3 for startup.
Again i did not find any problem in my files.
Now i changed:
update-initramfs -u -k all
as mentioned in other readmes and it worked.
This could be the mistake? I dont really know...