Description of problem:

In https://access.redhat.com/documentation/en/red-hat-ceph-storage/version-1.3/red-hat-ceph-storage-13-installation-guide-for-rhel-x86-64/#create-cluster we state the following.

"If at any point you run into trouble and you want to start over, execute the following to purge the configuration: 

ceph-deploy purgedata <ceph-node> [<ceph-node>]
ceph-deploy forgetkeys

To purge the Ceph packages too, you may also execute:

ceph-deploy purge <ceph-node> [<ceph-node>]

If you execute purge, you must re-install Ceph."

The actual case is that in order to run "purgedata" you must have uninstalled the ceph packages as this code and a quick test shows.

328 def purgedata(args):
329     LOG.debug(
330         'Purging data from cluster %s hosts %s',
331         args.cluster,
332         ' '.join(args.host),
333         )
334 
335     installed_hosts = []
336     for hostname in args.host:
337         distro = hosts.get(hostname, username=args.username)
338         ceph_is_installed = distro.conn.remote_module.which('ceph')
339         if ceph_is_installed:
340             installed_hosts.append(hostname)
341         distro.conn.exit()
342 
343     if installed_hosts:
344         LOG.error("Ceph is still installed on: %s", installed_hosts)
345         raise RuntimeError("refusing to purge data while Ceph is still installed")

$ ceph-deploy purgedata dell-per320-07
...
[ceph_deploy.install][ERROR ] Ceph is still installed on: ['dell-per320-07']
[ceph_deploy][ERROR ] RuntimeError: refusing to purge data while Ceph is still installed

"purgedata" is actually used to clean up /var/lib/ceph and /etc/ceph after ceph is uninstalled.

I believe the confusion comes from the upstream documentation for hammer here.

  http://docs.ceph.com/docs/hammer/rados/deployment/ceph-deploy-purge/

It states.

"Purge Data

To remove all data from /var/lib/ceph (but leave Ceph packages intact), execute the purgedata command.

    ceph-deploy purgedata {hostname} [{hostname} ...]"

I'll create a tracker for the upstream docs and link it here.

Version-Release number of selected component (if applicable):
1.3