Both adminDB and harvestDB if derby-based uses same derby.system.home value.
This has the consequence, that both databases uses the same derby.properties file and
and even worse the same derby.log

A workaround for this is creating a databasedir '$INSTALLDIR/admindatabasedir', moving the
adminDB into that directory, and adding the -Dderby.system.home=$INSTALLDIR/admindatabasedir

Then the adminDB will use the derby.properties in $INSTALLDIR/admindatabasedir, and the harvestDB will use the old derby.properties in $INSTALLDIR.

Each server will then also write to its own derby.log file.