6.13. Configuring a Quorum Disk


Quorum-disk parameters and heuristics depend on the site environment and the special requirements needed. To understand the use of quorum-disk parameters and heuristics, see the qdisk(5) man page. If you require assistance understanding and using quorum disk, contact an authorized Red Hat support representative.
Use the following command to configure your system for using a quorum disk:
ccs -h host --setquorumd [quorumd options]
Note that this command resets all other properties that you can set with the --setquorumd option to their default values, as described in Section 6.1.5, “Commands that Overwrite Previous Settings”.
Table 6.1, “Quorum Disk Options” summarizes the meaning of the quorum disk options you may need to set. For a complete list of quorum disk parameters, see the cluster schema at /usr/share/cluster/cluster.rng, and the annotated schema at /usr/share/doc/cman-X.Y.ZZ/cluster_conf.html.

Table 6.1. Quorum Disk Options

interval The frequency of read/write cycles, in seconds.
votes The number of votes the quorum daemon advertises to cman when it has a high enough score.
tko The number of cycles a node must miss to be declared dead.
min_score The minimum score for a node to be considered "alive". If omitted or set to 0, the default function, floor((n+1)/2), is used, where n is the sum of the heuristics scores. The Minimum Score value must never exceed the sum of the heuristic scores; otherwise, the quorum disk cannot be available.
device The storage device the quorum daemon uses. The device must be the same on all nodes.
label Specifies the quorum disk label created by the mkqdisk utility. If this field contains an entry, the label overrides the Device field. If this field is used, the quorum daemon reads /proc/partitions and checks for qdisk signatures on every block device found, comparing the label against the specified label. This is useful in configurations where the quorum device name differs among nodes.
Use the following command to configure the heuristics for a quorum disk:
ccs -h host --addheuristic [heuristic options]
Table 6.2, “Quorum Disk Heuristics” summarizes the meaning of the quorum disk heuristics you may need to set.

Table 6.2. Quorum Disk Heuristics

program The path to the program used to determine if this heuristic is available. This can be anything that can be executed by /bin/sh -c. A return value of 0 indicates success; anything else indicates failure. This parameter is required to use a quorum disk.
interval The frequency (in seconds) at which the heuristic is polled. The default interval for every heuristic is 2 seconds.
score The weight of this heuristic. Be careful when determining scores for heuristics. The default score for each heuristic is 1.
tko The number of consecutive failures required before this heuristic is declared unavailable.
To see a list of the quorum disk options and heuristics that are configured on a system, you can execute the following command:
ccs -h host --lsquorum
To remove a heuristic specified by a heuristic option, you can execute the following command:
ccs -h host rmheuristic [heuristic options]
Note that when you have finished configuring all of the components of your cluster, you will need to sync the cluster configuration file to all of the nodes, as described in Section 6.15, “Propagating the Configuration File to the Cluster Nodes”.


Syncing and activating propagates and activates the updated cluster configuration file. However, for the quorum disk to operate, you must restart the cluster (see Section 7.2, “Starting and Stopping a Cluster”), ensuring that you have restarted the qdiskd daemon on each node.