Re: [ceph-users] ceph mon_data_size_warn limits for large cluster

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On Thu, Feb 7, 2019 at 12:17 PM M Ranga Swami Reddy
<swamireddy@xxxxxxxxx> wrote:
>
> Hi Dan,
> >During backfilling scenarios, the mons keep old maps and grow quite
> >quickly. So if you have balancing, pg splitting, etc. ongoing for
> >awhile, the mon stores will eventually trigger that 15GB alarm.
> >But the intended behavior is that once the PGs are all active+clean,
> >the old maps should be trimmed and the disk space freed.
>
> old maps not trimmed after cluster reached to "all+clean" state for all PGs.
> Is there (known) bug here?
> As the size of dB showing > 15G, do I need to run the compact commands
> to do the trimming?

Compaction isn't necessary -- you should only need to restart all
peon's then the leader. A few minutes later the db's should start
trimming.

-- dan


>
> Thanks
> Swami
>
> On Wed, Feb 6, 2019 at 6:24 PM Dan van der Ster <dan@xxxxxxxxxxxxxx> wrote:
> >
> > Hi,
> >
> > With HEALTH_OK a mon data dir should be under 2GB for even such a large cluster.
> >
> > During backfilling scenarios, the mons keep old maps and grow quite
> > quickly. So if you have balancing, pg splitting, etc. ongoing for
> > awhile, the mon stores will eventually trigger that 15GB alarm.
> > But the intended behavior is that once the PGs are all active+clean,
> > the old maps should be trimmed and the disk space freed.
> >
> > However, several people have noted that (at least in luminous
> > releases) the old maps are not trimmed until after HEALTH_OK *and* all
> > mons are restarted. This ticket seems related:
> > http://tracker.ceph.com/issues/37875
> >
> > (Over here we're restarting mons every ~2-3 weeks, resulting in the
> > mon stores dropping from >15GB to ~700MB each time).
> >
> > -- Dan
> >
> >
> > On Wed, Feb 6, 2019 at 1:26 PM Sage Weil <sage@xxxxxxxxxxxx> wrote:
> > >
> > > Hi Swami
> > >
> > > The limit is somewhat arbitrary, based on cluster sizes we had seen when
> > > we picked it.  In your case it should be perfectly safe to increase it.
> > >
> > > sage
> > >
> > >
> > > On Wed, 6 Feb 2019, M Ranga Swami Reddy wrote:
> > >
> > > > Hello -  Are the any limits for mon_data_size for cluster with 2PB
> > > > (with 2000+ OSDs)?
> > > >
> > > > Currently it set as 15G. What is logic behind this? Can we increase
> > > > when we get the mon_data_size_warn messages?
> > > >
> > > > I am getting the mon_data_size_warn message even though there a ample
> > > > of free space on the disk (around 300G free disk)
> > > >
> > > > Earlier thread on the same discusion:
> > > > https://www.spinics.net/lists/ceph-users/msg42456.html
> > > >
> > > > Thanks
> > > > Swami
> > > >
> > > >
> > > >
> > > _______________________________________________
> > > ceph-users mailing list
> > > ceph-users@xxxxxxxxxxxxxx
> > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com



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