performance statistics - disk usage missing

Hi out there,

i'm dealing with performance statistics and managed to reactivate these graphs by using

service collectd restart
service rrdcached restart

Statistics are back without disk usage - ok thats not fine, but better than nothing. I checked raid-devices and was suprised by missing my md-device as well as system-device in webif.

cat /proc/mdstat

is fine.

What may i do?

regards,
Erik.