Do ceph have high availability, I config 2 node like this
cluster:
id: 07df97db-f315-4c78-9d2a-ab85007a1856
health: HEALTH_WARN
Reduced data availability: 32 pgs inactive
Degraded data redundancy: 374/590 objects degraded (63.390%), 18 pgs degraded, 32 pgs undersized
services:
mon: 2 daemons, quorum ceph1,ceph2
mgr: ceph1(active), standbys: ceph2
mds: mycephfs-1/1/1 up {0=ceph1=up:active}, 1 up:standby
osd: 2 osds: 1 up, 1 in
data:
pools: 6 pools, 96 pgs
objects: 216 objects, 12 MiB
usage: 75 MiB used, 945 MiB / 1020 MiB avail
pgs: 33.333% pgs not active
374/590 objects degraded (63.390%)
64 active+clean
18 undersized+degraded+peered
14 undersized+peered
As you can see i set up 2 mon call ceph1 and ceph2, but when i stop ceph1, the ceph2 is unable to write file into cephfs -mounted storage on VM
So how to make ceph high availability ?
Does is require more node or somethings like that ?
Best Answer
You need at least 3 MON to achieve HA because of the quorum. With only 2 nodes your storage will be stopped by an problem on one node.
"When a Ceph Storage Cluster runs multiple Ceph Monitors for high availability, Ceph Monitors use Paxos to establish consensus about the master cluster map. A consensus requires a majority of monitors running to establish a quorum for consensus about the cluster map (e.g., 1; 2 out of 3; 3 out of 5; 4 out of 6; etc.)." link
If you need HA storage with 2 nodes take a look at solutions which has been designed for this. I can recommend StarWind VSAN free with active-active replication and no quorum requirement.