Description of problem:
-----------------------

While running CBT , the script errored out with the following error message on stdout :

<snip>

Traceback (most recent call last):
  File "/home/ceph/cbt/cbt.py", line 71, in main
    b.run()
  File "/home/ceph/cbt/benchmark/radosbench.py", line 67, in run
    self.mkpools()
  File "/home/ceph/cbt/benchmark/radosbench.py", line 160, in mkpools
    self.cluster.rmpool('rados-bench-cbt', self.pool_profile)
  File "/home/ceph/cbt/cluster/ceph.py", line 636, in rmpool
    continue_if_error=False).communicate()
  File "/home/ceph/cbt/common.py", line 33, in communicate
    raise Exception(str(self)+'\nstdout:\n'+stdoutdata+'\nstderr\n'+stderrdata)
Exception: checked_Popen args=['pdsh', '-S', '-f', '1', '-R', 'ssh', '-w', 'ceph@gqac016', 'sudo /usr/bin/ceph -c /tmp/cbt/ceph/ceph.conf osd pool delete rados-bench-cbt rados-bench-cbt --yes-i-really-really-mean-it'] continue_if_error=False rtncode=1
stdout:

stderr
gqac016: Error EPERM: pool deletion is disabled; you must first set the mon_allow_pool_delete config option to true before you can destroy a pool
pdsh@gqac016: gqac016: ssh exited with exit code 1

</snip>

This is a change introduced in CEPH 3.0 developer bits.

For successful pool deletion,I think it's good to include this in the admin guide in appropriate places.