If the installation comes to "Partition method", use "Manual".
# In the following menu, scroll to yo... pe.
# In the "Partition settings" menu, go to "Use as" and hit enter.
# Change the type to "physi... artitions (beside swap) should be marked for RAID use.
# Now look at the first menu entry in the pa... ith "Yes".
# Now pick "Create MD device".
# Use RAID1 and give the number of active and spare dev