The Proxmox cluster filesystem (pmxcfs) in short is an integral part of how a Proxmox cluster functions. As the name implies, it is basically a common filesystem shared among all the nodes in a Proxmox cluster. Pmxcfs is a SQLite database-driven filesystem where all the Proxmox configuration files are stored. Any changes to these files are replicated in real time using the corosync cluster engine.
Note
For more information on corosync, visit https://en.wikipedia.org/wiki/Corosync_Cluster_Engine.
To understand pmxcfs, we are going to take a look at how the directory structure is laid out in the filesystem. Pmxcfs can be accessed from any nods in the cluster. Log in as the root into a node through SSH or the Proxmox GUI | Shell.