Bases teóricas

The Red Hat Cluster Manager provides the following daemons to monitor cluster operation:

• cluquorumd— Quorum daemon

• clusvcmgrd— Service manager daemon

• clurmtabd— Synchronizes NFS mount entries in/var/lib/nfs/rmtabwith a private copy on a service’s mount point

• clulockd— Global lock manager (the only client of this daemon isclusvcmgrd)

• clumembd— Membership daemon

Each of these daemons can be individually configured using theCluster Configuration Tool. To access theCluster Daemon Propertiesdialog box, chooseCluster=>Daemon Properties. The following sections explain how to configure cluster daemon properties. However, note that the default values are applicable to most configurations and do not need to be changed.

3.6.1. Configuring clumembd

On each cluster system, theclumembddaemon issues heartbeats (pings) across the point-to-point Ethernet lines to which the cluster members are connected.

Chapter 3. Cluster Configuration 43

Figure 3-8. Configuringclumembd

Note

You can enable both broadcast heartbeating and multicast heartbeating, butat least oneof these features must be used.

Multicast heartbeating over a channel-bonded Ethernet interface provides good fault tolerance and is recommended for availability.

You can specify the following properties for theclumembddaemon:

• Log Level— Determines the level of event messages that get logged to the cluster log file (by de- fault/var/log/messages). Choose the appropriate logging level from the menu. Refer to Section 3.12ConfiguringsyslogdEvent Loggingfor more information.

• Failover Speed—Determines the number of seconds that the cluster service waits before shutting down a non-responding member (that is, a member from which no heartbeat is detected). To set the failover speed, drag the slider bar. The default failover speed is 10 seconds.

Note

Setting a faster failover speed increases the likelihood of false shutdowns.

• Heartbeating —Enable Broadcast HeartbeatingorEnable Multicast Heartbeatingby clicking the corresponding radio button. Broadcast heartbeating specifies that the broadcast IP address is to be used by theclumembddaemon when emitting heartbeats.

By default, theclumembdis configured to emit heartbeats via multicast. Multicast uses the network interface associated with the member’s hostname for transmission of heartbeats.

• Multicast IP Address— Specifies the IP address to be used by theclumembddaemon over the multicast channel. This field is not editable ifEnable Broadcast Heartbeatingis checked. The default multicast IP address used by the cluster is 225.0.0.11.

3.6.2. Configuring cluquorumd

In a two-member cluster without a specified tiebreaker IP address, thecluquorumddaemon peri- odically writes a time-stamp and system status to a specific area on the primary and shadow shared

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partitions. The daemon also reads the other member’s timestamp and system status information from the primary shared partition or, if the primary partition is corrupted, from the shadow partition.

Figure 3-9. Configuringcluquorumd

You can specify the following properties for thecluquorumddaemon:

• Log Level— Determines the level of event messages that get logged to the cluster log file (by de- fault/var/log/messages). Choose the appropriate logging level from the menu. Refer to Section 3.12ConfiguringsyslogdEvent Loggingfor more information.

• Ping IntervalorTiebreaker IP—Ping Intervalis used for a disk-based heartbeat; specifies the number of seconds between the quorum daemon’s updates to its on-disk status.

Tiebreaker IPis a network-based heartbeat used to determine quorum, which is the ability to run services. The tiebreaker IP address is only checked when the cluster has an even split in a two- or four-member cluster. This IP address should be associated with a router that, during normal operation, can be reached by all members over the Ethernet interface used by the cluster software.

3.6.3. Configuring clurmtabd

Theclurmtabddaemon synchronizes NFS mount entries in/var/lib/nfs/rmtabwith a private copy on a service’s mount point. Theclurmtabddaemon runs only when a service with NFS exports is running.

Figure 3-10. Configuringclurmtabd

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• Log Level— Determines the level of event messages that get logged to the cluster log file (by default,/var/log/messages). Choose the appropriate logging level from the menu. See Section 3.12ConfiguringsyslogdEvent Loggingfor more information.

• Poll Interval—Specifies the number of seconds between polling cycles to synchronize the local NFSrmtabto the clusterrmtabon shared storage.

3.6.4. Configuring the clusvcmgrd daemon

On each cluster system, theclusvcmgrdservice manager daemon responds to changes in clus- ter membership by stopping and starting services. You might notice, at times, that more than one clusvcmgrdprocess is running; separate processes are spawned forstart,stop, andmonitoring operations.

Figure 3-11. Configuringclusvcmgrd

You can specify the following properties for theclusvcmgrddaemon:

• Log Level— Determines the level of event messages that get logged to the cluster log file (by default,/var/log/messages). Choose the appropriate logging level from the menu. See Section 3.12ConfiguringsyslogdEvent Loggingfor more information.

3.6.5. Configuring clulockd

Theclulockddaemon manages the locks on files being accessed by cluster members.

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You can specify the following properties for theclulockddaemon:

• Log Level— Determines the level of event messages that get logged to the cluster log file (by default,/var/log/messages). Choose the appropriate logging level from the menu. See Section 3.12ConfiguringsyslogdEvent Loggingfor more information.