The following diagram is a basic representation of Proxmox and a Ceph cluster. Note that both the clusters are on separate subnets on separate switches:

A Ceph cluster should be set up with a separate subnet on a separate switch to keep it isolated from the Proxmox public subnet and for optimal Ceph cluster functioning. The Ceph Sync LAN is used by Ceph primarily to sync data between OSDs. The Ceph Public LAN is used primarily to serve user requests for data from Ceph into Proxmox VMs. The advantage of this practice is to keep Ceph's internal traffic isolated so that it does not interfere with the traffic of the running virtual machines. On a healthy Ceph cluster with the active+clean state, this is not an issue. However, when Ceph goes into self-healing mode due to an OSD or node failure, it rebalances itself by redistributing PGs among remaining...