Upon (re-)start of DUCC, one machine showed status as "defined" on the Machines page and "unknown" on Daemons page in ducc-mon.
Examination of the Agent's log revealed:
host.domain.net.agent.log:java.io.FileNotFoundException: /cgroup/ducc/327204.327204.28574/cgroup.procs (No such file or directory)
Also, manually attempting to run
/bin/cgcreate -t degenaro:mygroup -a degenaro:mygroup -g memory,cpu:ducc/test
/bin/cgcreate: can't create cgroup ducc/test: Cgroup, operation not allowed
This may be due to Agent attempting to clean-up processes from previous lifetime, but is unable to do so.