Re: ceph orch host drain daemon type

[Eugen Block <eblock@xxxxxx>]

Hi,

> What would be nice is if the drain command could take care of OSDs  
> by default and drain all services only when called with a  
> --remove-all-services flag or something similar.

but that would mean that you wouldn't be able to drain only specific  
services, and OSDs would be drained either way. From my perspective,  
it would suffice to have the --daemon-type flag which is already  
present in 'ceph orch ps --daemon-type' command. You could either  
drain a specific daemon-type or drain the entire host (can be the  
default with the same behaviour as it currently works). That would  
allow more control about non-osd daemons.

Zitat von Frédéric Nass <frederic.nass@xxxxxxxxxxxxxxxx>:

> Hi Robert,
>
> Thanks for the suggestion. Unfortunately, removing the 'osds' label  
> from a host does not remove the OSDs, unlike with other labels  
> (mons, mgrs, mdss, nfss, crash, _admin, etc.). This is because this  
> kind of service is tightly bound to the host and less 'portable'  
> than other services, I think. This is likely the purpose of the  
> drain command.
>
> What would be nice is if the drain command could take care of OSDs  
> by default and drain all services only when called with a  
> --remove-all-services flag or something similar.
>
> Frédéric
>
> ----- Le 30 Aoû 24, à 1:07, Robert W. Eckert rob@xxxxxxxxxxxxxxx a écrit :
>
> > If you are using cephadm, couldn't the host be removed from placing  
> > osds? On my
> > cluster, I labeled the hosts for each service (OSD/MON/MGR/...) and have the
> > services deployed by label.   I believe that if you had that, then  
> > when a label
> > is removed from the host the services eventually drain.
> >
> >
> >
> > -----Original Message-----
> > From: Frédéric Nass <frederic.nass@xxxxxxxxxxxxxxxx>
> > Sent: Thursday, August 29, 2024 11:30 AM
> > To: Eugen Block <eblock@xxxxxx>
> > Cc: ceph-users <ceph-users@xxxxxxx>; dev <dev@xxxxxxx>
> > Subject:  Re: ceph orch host drain daemon type
> >
> > Hello Eugen,
> >
> > A month back, while playing with a lab cluster, I drained a  
> > multi-service host
> > (OSDs, MGR, MON, etc.) in order to recreate all of its OSDs. During this
> > operation, all cephadm containers were removed as expected,  
> > including the MGR.
> > As a result, I got into a situation where the orchestrator backend 'cephadm'
> > was missing and wouldn't load anymore. I didn't have much time to  
> > investigate
> > this, so I decided to recreate the lab cluster. But I think this is due to a
> > bug.
> >
> > I would probably have avoided this situation if I had been able to ask the
> > orchestrator to only drain services of type 'osd'. Makes sense.
> >
> > Cheers,
> > Frédéric.
> >
> > ----- Le 27 Aoû 24, à 15:19, Eugen Block eblock@xxxxxx a écrit :
> >
> > > Hi,
> > >
> > > is there anything on the road map to be able to choose a specific
> > > daemon type to be entirely removed from a host instead of all cephadm
> > > managed daemons? I just did a quick search in tracker and github, but
> > > it may be "hidden" somewhere else.
> > >
> > > I was thinking about colocated daemons on a host, for example MON,
> > > MGR, OSDs, node-exporter, crash. That's quite common, but if I just
> > > wanted to drain all OSDs (maybe mark them as "destroyed" in order to
> > > replace the drives), the usual 'ceph orch host drain <host>' command
> > > would remove all daemons. That seems unnecessary if I'm going to add
> > > the OSDs back.
> > >
> > > Since there are a couple of other daemon types which can be deployed
> > > multiple times per host, e. g. MDS, RGW, it doesn't only make sense
> > > for OSDs but for other daemons as well. And those other daemons
> > > usually have some cryptic suffix, we wouldn't need that in order to
> > > get rid of them, it doesn't save that much time, but it could be a
> > > nice enhancement.
> > >
> > > Should I create a tracker issue in the enhancement section for that?
> > >
> > > Thanks!
> > > Eugen
> > > _______________________________________________
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