1 Proxmox Cluster file system (pmxcfs)
2 ====================================
4 The Proxmox Cluster file system (pmxcfs) is a database-driven file
5 system for storing configuration files, replicated in real time to all
6 cluster nodes using corosync. We use this to store all PVE related
9 Although the file system stores all data inside a persistent database
10 on disk, a copy of the data resides in RAM. That imposes restriction
11 on the maximal size, which is currently 30MB. This is still enough to
12 store the configuration of several thousand virtual machines.
17 * seamless replication of all configuration to all nodes in real time
18 * provides strong consistency checks to avoid duplicate VM IDs
19 * read-only when a node looses quorum
20 * automatic updates of the corosync cluster configuration to all nodes
21 * includes a distributed locking mechanism
26 The file system is based on FUSE, so the behavior is POSIX like. But
27 some feature are simply not implemented, because we do not need them:
29 * you can just generate normal files and directories, but no symbolic
32 * you can't rename non-empty directories (because this makes it easier
33 to guarantee that VMIDs are unique).
35 * you can't change file permissions (permissions are based on path)
37 * `O_EXCL` creates were not atomic (like old NFS)
39 * `O_TRUNC` creates are not atomic (FUSE restriction)
45 All files and directories are owned by user 'root' and have group
46 'www-data'. Only root has write permissions, but group 'www-data' can
47 read most files. Files below the following paths:
50 /etc/pve/nodes/${NAME}/priv/
52 are only accessible by root.
57 We use the http://www.corosync.org[Corosync Cluster Engine] for
58 cluster communication, and http://www.sqlite.org[SQlite] for the
59 database file. The filesystem is implemented in user space using
60 http://fuse.sourceforge.net[FUSE].
65 The file system is mounted at:
72 [width="100%",cols="m,d"]
74 |corosync.conf |corosync cluster configuration file (previous to {pve} 4.x this file was called cluster.conf)
75 |storage.cfg |{pve} storage configuration
76 |user.cfg |{pve} access control configuration (users/groups/...)
77 |domains.cfg |{pve} Authentication domains
78 |authkey.pub | public key used by ticket system
79 |priv/shadow.cfg | shadow password file
80 |priv/authkey.key | private key used by ticket system
81 |nodes/<NAME>/pve-ssl.pem | public ssl key for web server
82 |nodes/<NAME>/priv/pve-ssl.key | private ssl key
83 |nodes/<NAME>/qemu-server/<VMID>.conf | VM configuration data for KVM VMs
84 |nodes/<NAME>/lxc/<VMID>.conf | VM configuration data for LXC containers
85 |firewall/cluster.fw | Firewall config applied to all nodes
86 |firewall/<NAME>.fw | Firewall config for individual nodes
87 |firewall/<VMID>.fw | Firewall config for VMs and Containers
93 [width="100%",cols="m,m"]
95 |local |nodes/<LOCAL_HOST_NAME>
96 |qemu-server |nodes/<LOCAL_HOST_NAME>/qemu-server/
97 |lxc |nodes/<LOCAL_HOST_NAME>/lxc/
100 Special status files for debugging (JSON)
101 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
103 [width="100%",cols="m,d"]
105 | .version |file versions (to detect file modifications)
106 | .members |Info about cluster members
107 | .vmlist |List of all VMs
108 | .clusterlog |Cluster log (last 50 entries)
109 | .rrd |RRD data (most recent entries)
112 Enable/Disable debugging
113 ~~~~~~~~~~~~~~~~~~~~~~~~
115 You can enable verbose syslog messages with:
117 echo "1" >/etc/pve/.debug
119 And disable verbose syslog messages with:
121 echo "0" >/etc/pve/.debug
127 If you have major problems with your Proxmox VE host, e.g. hardware
128 issues, it could be helpful to just copy the pmxcfs database file
129 /var/lib/pve-cluster/config.db and move it to a new Proxmox VE
130 host. On the new host (with nothing running), you need to stop the
131 pve-cluster service and replace the config.db file (needed permissions
132 0600). Second, adapt '/etc/hostname' and '/etc/hosts' according to the
133 lost Proxmox VE host, then reboot and check. (And donĀ“t forget your
136 Remove Cluster configuration
137 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
139 The recommended way is to reinstall the node after you removed it from
140 your cluster. This makes sure that all secret cluster/ssh keys and any
141 shared configuration data is destroyed.
143 In some cases, you might prefer to put a node back to local mode
144 without reinstall, which is described here:
146 * stop the cluster file system in '/etc/pve/'
148 # systemctl stop pve-cluster
150 * start it again but forcing local mode
154 * remove the cluster config
156 # rm /etc/pve/cluster.conf
157 # rm /etc/cluster/cluster.conf
158 # rm /var/lib/pve-cluster/corosync.authkey
160 * stop the cluster file system again
162 # service pve-cluster stop
164 * restart pve services (or reboot)
166 # service pve-cluster start
167 # service pvedaemon restart
168 # service pveproxy restart
169 # service pvestatd restart