Libro sobre Proxmox maestria
Chapter 2
The <cluster>..</cluster> tag acts as the main body of the configuration file. All other syntaxes reside inside this tag. The beginning of this tag shows the name of the cluster as name="pmx-cluster" and the config file version number as config _version="2". This number represents how many times the file has been changed. Each change increases the version number incrementally:
<cman keyfile="/var/lib/pve-cluster/corosync.authkey"></cman>
The <cman> tag represents the location of authorization key file for Corosync. This key file is needed by Corosync for authentication within cluster communication from one node to another.
Now have a look at the following code:
<clusternodes>
<clusternode name="pmxvm01" votes="1" nodeid="1"/> <clusternode name="pmxvm02" votes="1" nodeid="2"/> </clusternodes>
The <clusternode> tag shows the names of all the member nodes in the cluster, node ID, and expected votes to form Quorum. In order to have a healthy cluster or the cluster to be ready, it is very important to form Quorum. A cluster has a specific number of nodes and each node is considered as one vote. When majority (over 50 percent) of the votes or nodes are available, Quorum is achieved. If the number of votes falls below the majority, the cluster stops providing services. But nodes will continue listening for incoming connections from other nodes in case failed nodes appear again on the network.
When Quorum is lost, pmxcfs becomes inaccessible to prevent data inconsistency. If it is very important to access the pmxcfs on a node when Quorum is lost, then executing the following command on the same node will form a Quorum: #pvecm expected 1
This command will let the node know that only one vote is expected to have Quorum, even though there are other nodes in the cluster.
A Quorum is the minimum number of nodes needed to achieve a healthy cluster. Proxmox needs a minimum of three nodes to form a Quorum, or a shared storage system to store a Quorum disk for a two-node cluster.
Although not recommended, it is possible to create a Proxmox cluster with just two nodes and achieve High Availability. Look into the Wiki page at http://pve. proxmox.com/wiki/Two-Node_High_Availability_Cluster to get details on how to create a two-node High Availability cluster.
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