On Tue, Jun 4, 2019 at 6:22 AM Jan Fajerski <jfajerski@xxxxxxxx> wrote: > > Hi list, > I came across some strange MDS behaviour recently where it is not possible to > start and MDS on a machine that happens to have the hostname "admin". > > This turns out to be this code > https://github.com/ceph/ceph/blob/master/src/common/entity_name.cc#L128 that is > called by ceph-mds here > https://github.com/ceph/ceph/blob/master/src/ceph_mds.cc#L116. > > Together with the respective systemd unit file (passing "--id %i") this prevents > starting an MDS on a machine witht he hostname admin. > > Is this just old code and chance or is there a reason behind this? The MDS is > the only daemon doing that, though I did not check for other but similar checks > in other daemons. There's a pretty funny trail of updates there, but it's still basically what we see in the MDS code: it doesn't want to turn on if it doesn't have a specified name. "admin" is the default (ie, client.admin) and so the checker is incorrectly flagging it as being unnamed when the name is derived from a host short name "admin". I'm not sure there's a good way to deal with that — we really *don't* want somebody's misconfigured cluster to start up a bunch of MDSes that all display as "mds.admin"! -Greg > > Best, > Jan > > -- > Jan Fajerski > Engineer Enterprise Storage > SUSE Linux GmbH, GF: Felix Imendörffer, Mary Higgins, Sri Rasiah > HRB 21284 (AG Nürnberg)
