/opt is a location where external drive is expected to be mounted. Check why it is not mounted.
/tmp is located in RAM
I checked out the tutorial here but it's not working for me. /opt isn't writeable.
My setup is WL-500W with Oleg 1.9.2.7-8 plus one external hard drive (250GB ext3 formatted).
I tried using the tutorial with /tmp instead of /opt, but, surprise, surprise, everything disappeared through the reboot. And even before reboot, the smb server didn't seem to be, well, serving.
/opt is a location where external drive is expected to be mounted. Check why it is not mounted.
/tmp is located in RAM