tried to do backup to CD-RW

mkfifo /tmp/backup
/sbin/dump -0 -u -h 0 -B 666000 -L "wojtek" -f /tmp/backup /

on one console

cdrecord -v -dao tsize=666000k /tmp/backup

recorded one disk, then dump said "Closing /tmp/backup" and waits forever

fstat /tmp/backup shows it's not open.

what i missed?