ifdef::manvolnum[] PVE({manvolnum}) ================ include::attributes.txt[] NAME ---- pmxcfs - Proxmox Cluster File System SYNOPSYS -------- include::pmxcfs.8-cli.adoc[] DESCRIPTION ----------- endif::manvolnum[] ifndef::manvolnum[] Proxmox Cluster File System (pmxcfs) ==================================== include::attributes.txt[] endif::manvolnum[] The Proxmox Cluster file system (pmxcfs) is a database-driven file system for storing configuration files, replicated in real time to all cluster nodes using corosync. We use this to store all PVE related configuration files. Although the file system stores all data inside a persistent database on disk, a copy of the data resides in RAM. That imposes restriction on the maximal size, which is currently 30MB. This is still enough to store the configuration of several thousand virtual machines. This system provides the following advantages: * seamless replication of all configuration to all nodes in real time * provides strong consistency checks to avoid duplicate VM IDs * read-only when a node loses quorum * automatic updates of the corosync cluster configuration to all nodes * includes a distributed locking mechanism POSIX Compatibility ------------------- The file system is based on FUSE, so the behavior is POSIX like. But some feature are simply not implemented, because we do not need them: * you can just generate normal files and directories, but no symbolic links, ... * you can't rename non-empty directories (because this makes it easier to guarantee that VMIDs are unique). * you can't change file permissions (permissions are based on path) * `O_EXCL` creates were not atomic (like old NFS) * `O_TRUNC` creates are not atomic (FUSE restriction) File access rights ------------------ All files and directories are owned by user 'root' and have group 'www-data'. Only root has write permissions, but group 'www-data' can read most files. Files below the following paths: /etc/pve/priv/ /etc/pve/nodes/${NAME}/priv/ are only accessible by root. Technology ---------- We use the http://www.corosync.org[Corosync Cluster Engine] for cluster communication, and http://www.sqlite.org[SQlite] for the database file. The filesystem is implemented in user space using http://fuse.sourceforge.net[FUSE]. File system layout ------------------ The file system is mounted at: /etc/pve Files ~~~~~ [width="100%",cols="m,d"] |======= |corosync.conf |corosync cluster configuration file (previous to {pve} 4.x this file was called cluster.conf) |storage.cfg |{pve} storage configuration |datacenter.cfg |{pve} datacenter wide configuration (keyboard layout, proxy, ...) |user.cfg |{pve} access control configuration (users/groups/...) |domains.cfg |{pve} Authentication domains |authkey.pub | public key used by ticket system |pve-root-ca.pem | public certificate of cluster CA |priv/shadow.cfg | shadow password file |priv/authkey.key | private key used by ticket system |priv/pve-root-ca.key | private key of cluster CA |nodes//pve-ssl.pem | public ssl certificate for web server (signed by cluster CA) |nodes//pve-ssl.key | private ssl key for pve-ssl.pem |nodes//pveproxy-ssl.pem | public ssl certificate (chain) for web server (optional override for pve-ssl.pem) |nodes//pveproxy-ssl.key | private ssl key for pveproxy-ssl.pem (optional) |nodes//qemu-server/.conf | VM configuration data for KVM VMs |nodes//lxc/.conf | VM configuration data for LXC containers |firewall/cluster.fw | Firewall config applied to all nodes |firewall/.fw | Firewall config for individual nodes |firewall/.fw | Firewall config for VMs and Containers |======= Symbolic links ~~~~~~~~~~~~~~ [width="100%",cols="m,m"] |======= |local |nodes/ |qemu-server |nodes//qemu-server/ |lxc |nodes//lxc/ |======= Special status files for debugging (JSON) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [width="100%",cols="m,d"] |======= | .version |file versions (to detect file modifications) | .members |Info about cluster members | .vmlist |List of all VMs | .clusterlog |Cluster log (last 50 entries) | .rrd |RRD data (most recent entries) |======= Enable/Disable debugging ~~~~~~~~~~~~~~~~~~~~~~~~ You can enable verbose syslog messages with: echo "1" >/etc/pve/.debug And disable verbose syslog messages with: echo "0" >/etc/pve/.debug Recovery -------- If you have major problems with your Proxmox VE host, e.g. hardware issues, it could be helpful to just copy the pmxcfs database file /var/lib/pve-cluster/config.db and move it to a new Proxmox VE host. On the new host (with nothing running), you need to stop the pve-cluster service and replace the config.db file (needed permissions 0600). Second, adapt '/etc/hostname' and '/etc/hosts' according to the lost Proxmox VE host, then reboot and check. (And donĀ“t forget your VM/CT data) Remove Cluster configuration ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The recommended way is to reinstall the node after you removed it from your cluster. This makes sure that all secret cluster/ssh keys and any shared configuration data is destroyed. In some cases, you might prefer to put a node back to local mode without reinstall, which is described here: * stop the cluster file system in '/etc/pve/' # systemctl stop pve-cluster * start it again but forcing local mode # pmxcfs -l * remove the cluster config # rm /etc/pve/cluster.conf # rm /etc/cluster/cluster.conf # rm /var/lib/pve-cluster/corosync.authkey * stop the cluster file system again # systemctl stop pve-cluster * restart pve services (or reboot) # systemctl start pve-cluster # systemctl restart pvedaemon # systemctl restart pveproxy # systemctl restart pvestatd ifdef::manvolnum[] include::pve-copyright.adoc[] endif::manvolnum[]