Comment 8 for bug 23203

I fixed this on my system by adding a udev rule. You could simply add the necessary line in 40-permissions.rules but if there is an update to udev it will get overwritten and you'll be back where you started. So I created a new rule and called it 15-local.rules and put the following lines in the file:

# SCSI devices
BUS=="scsi", KERNEL=="sg[0-9]", NAME="%k", GROUP="cdrom"

Restart the system and in terminal run cdrecord -scanbus. You should no longer see the line"Error trying to open /dev/sg0 exclusively (Permission denied)".