Node redundancy on ceph.

Hello,
I'm new in proxmox and I just deploy the Promox with 5 nodes with installed ceph on all nodes.
ceph is configured with 5 monitors.

Facing issue while I shutdown 1 node VM installed on ceph storage migrate automatic to next available node. But when shutdown 2 nodes my ceph storage is not accessible in cluster. So what I should to look?

Thanks in advance.