Hi,

On Mon, Apr 13, 2020 at 3:08 PM Frank Schilder <fr...@dtu.dk> wrote:
>
> Hi Paul,
>
> thanks for the fast reply. When you say "bit 21", do you mean "(feature_map & 
> 2^21) == true" (i.e., counting from 0 starting at the right-hand end)?

yes

> Assuming upmap is supported by all clients. If I understand correctly, to use 
> the upmap mode with balancer, I need to set
>
> ceph osd set-require-min-compat-client luminous
>
> Which I would guess will not allow the jewel clients to reconnect. I would be 
> grateful if you could clarify these points to me:

yes

> 1) Can I use up-map mode without setting this?

no

> 2) If so, what happens if a jewel client without this feature bit set tries 
> to connect?

it'll error out with a message about feature mismatch; it checks
actually relevant feature flags not the reverse mapping to a release
which is usually wrong for kernel clients

> 3) I guess that in case that as soon as an up-map table is created, only 
> clients with this bit set can connect. In case we run into problems, is there 
> a way to roll back?

yes, you can remove the upmap items manually and change the client
requirement; I don't know the command to do this off the top of my
head


Paul

-- 
Paul Emmerich

Looking for help with your Ceph cluster? Contact us at https://croit.io

croit GmbH
Freseniusstr. 31h
81247 München
www.croit.io
Tel: +49 89 1896585 90

>
> Many thanks and best regards,
>
> =================
> Frank Schilder
> AIT Risø Campus
> Bygning 109, rum S14
>
> ________________________________________
> From: Paul Emmerich <paul.emmer...@croit.io>
> Sent: 13 April 2020 13:32:40
> To: Frank Schilder
> Cc: ceph-users
> Subject: Re: [ceph-users] Check if upmap is supported by client?
>
> bit 21 in the features bitmap is upmap support
>
> Paul
>
> --
> Paul Emmerich
>
> Looking for help with your Ceph cluster? Contact us at https://croit.io
>
> croit GmbH
> Freseniusstr. 31h
> 81247 München
> www.croit.io
> Tel: +49 89 1896585 90
>
> On Mon, Apr 13, 2020 at 11:53 AM Frank Schilder <fr...@dtu.dk> wrote:
> >
> > Dear all,
> >
> > I would like to enable the balancer on a mimic 13.2.8 cluster in upmap 
> > mode. Unfortunately, I have a lot of ceph fs kernel clients that report 
> > their version as jewel, but might already support upmap. The ceph client 
> > kernel module received already a lot of back-ports and supports features of 
> > later ceph versions, for example, quotas. I guess they report back jewel, 
> > because not all luminous/mimic features are back-ported yet. Is there a way 
> > to check if a client supports upmap?
> >
> > Here some info:
> >
> > [root@gnosis ~]# ceph features
> > {
> >     [...]
> >      "client": [
> >         {
> >             "features": "0x27018fb86aa42ada",
> >             "release": "jewel",
> >             "num": 1676
> >         },
> >         {
> >             "features": "0x2f018fb86aa42ada",
> >             "release": "luminous",
> >             "num": 1
> >         },
> >         {
> >             "features": "0x3ffddff8ffacfffb",
> >             "release": "luminous",
> >             "num": 167
> >         }
> >     ],
> >
> > The fs clients are the top two entries, the third entry is rbd clients. 
> > Note that the feature key for the fs clients is almost identical. Here a 
> > snippet from mds session ls for one such jewel client:
> >
> >     {
> >         "id": 25641514,
> >         "num_leases": 0,
> >         "num_caps": 1,
> >         "state": "open",
> >         "request_load_avg": 0,
> >         "uptime": 588563.550276,
> >         "replay_requests": 0,
> >         "completed_requests": 0,
> >         "reconnecting": false,
> >         "inst": "client.25641514 192.168.57.124:0/3398308464",
> >         "client_metadata": {
> >             "features": "00000000000000ff",
> >             "entity_id": "con-fs2-hpc",
> >             "hostname": "sn253.hpc.ait.dtu.dk",
> >             "kernel_version": "3.10.0-957.12.2.el7.x86_64",
> >             "root": "/hpc/groups"
> >         }
> >     }
> >
> > Since I would like to use upmap right from the beginning, my alternative is 
> > to re-weight a few of the really bad outliers manually to simplify changing 
> > back.
> >
> > What would you suggest?
> >
> > Thanks and best regards,
> >
> > =================
> > Frank Schilder
> > AIT Risø Campus
> > Bygning 109, rum S14
> > _______________________________________________
> > ceph-users mailing list -- ceph-users@ceph.io
> > To unsubscribe send an email to ceph-users-le...@ceph.io
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