Dear Cephalopodians,
I have two questions about RBD mirroring.
1) I can not get it to work - my setup is:
- One cluster holding the live RBD volumes and snapshots, in pool "rbd", cluster name "ceph",
running latest Mimic.
I ran "rbd mirror pool enable rbd pool" on that cluster and created a cephx user "rbd_mirror" with (is there a better way?):
ceph auth get-or-create client.rbd_mirror mon 'allow r' osd 'allow class-read object_prefix rbd_children, allow pool rbd r' -o ceph.client.rbd_mirror.keyring --cluster ceph
In that pool, two images have the journaling feature activated, all others have it disabled still (so I would expect these two to be mirrored).
- Another (empty) cluster running latest Nautilus, cluster name "ceph", pool "rbd".
I've used the dashboard to activate mirroring for the RBD pool, and then added a peer with cluster name "ceph-virt", cephx-ID "rbd_mirror", filled in the mons and key created above.
I've then run:
ceph auth get-or-create client.rbd_mirror_backup mon 'allow r' osd 'allow class-read object_prefix rbd_children, allow pool rbd rwx' -o client.rbd_mirror_backup.keyring --cluster ceph
and deployed that key on the rbd-mirror machine, and started the service with:
systemctl start ceph-rbd-mirror@rbd_mirror_backup.service
After this, everything looks fine:
# rbd mirror pool info
Mode: pool
Peers:
UUID NAME CLIENT
XXXXXXXXXXX ceph-virt client.rbd_mirror
The service also seems to start fine, but logs show (debug rbd_mirror=20):
rbd::mirror::ClusterWatcher:0x5575e2a7d390 resolve_peer_config_keys: retrieving config-key: pool_id=2, pool_name=rbd, peer_uuid=XXXXXXXXXXX
rbd::mirror::Mirror: 0x5575e29c7240 update_pool_replayers: enter
rbd::mirror::Mirror: 0x5575e29c7240 update_pool_replayers: restarting failed pool replayer for uuid: XXXXXXXXXXX cluster: ceph-virt client: client.rbd_mirror
rbd::mirror::PoolReplayer: 0x5575e2a7da20 init: replaying for uuid: XXXXXXXXXXX cluster: ceph-virt client: client.rbd_mirror
rbd::mirror::PoolReplayer: 0x5575e2a7da20 init_rados: error connecting to remote peer uuid: XXXXXXXXXXX cluster: ceph-virt client: client.rbd_mirror: (95) Operation not supported
rbd::mirror::ServiceDaemon: 0x5575e29c8d70 add_or_update_callout: pool_id=2, callout_id=2, callout_level=error, text=unable to connect to remote cluster
I already tried storing the ceph.client.rbd_mirror.keyring (i.e. from the cluster with the live images) on the rbd-mirror machine explicitly (i.e. not only in mon config storage),
and after doing that:
rbd -m mon_ip_of_ceph_virt_cluster --id=rbd_mirror ls
works fine. So it's not a connectivity issue. Maybe a permission issue? Or did I miss something?
Any idea what "operation not supported" means?
It's unclear to me whether things should work well using Mimic with Nautilus, and enabling pool mirroring but only having journaling on for two images is a supported case.
2) Since there is a performance drawback (about 2x) for journaling, is it also possible to only mirror snapshots, and leave the live volumes alone?
This would cover the common backup usecase before deferred mirroring is implemented (or is it there already?).
Cheers and thanks in advance,
Oliver
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