Tente remover: GroupBy "Type"
e isso deve funcionar.
De acordo com a documentação do plug-in de agregação collectd :
There are a couple of limitations you should be aware of:
The Type cannot be left unspecified, because it is not reasonable to add apples to oranges. Also, the internal lookup structure won't work if you try to group by type.
There must be at least one unspecified, ungrouped field. Otherwise nothing will be aggregated.