My database is nomount and i want to restore controlfile
my backup is store in a tape.
When I connect to RMAN and my terget database I run this :

run {
allocate channel t1 type 'sbt_tape'
parms 'ENV=(NSR_SERVER=toto.com,NSR_DATA_VOLUME_POOL=Default)';
restore controlfile;
release channel t1;
}