<family_name>-0..9 when number of nodes <= 10
  <family_name>-01..09 (or n) when number of nodes > 10

In scalability tests instance keeps track of old used nodes and when nodes > 10
will pick by default sort "activity-0" which is NO longer an existing zope process.
This is an ugly fix and real woraround is to have something like activities-000x schema by default