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Note
Using JBOD as a quorum disk is not recommended. A JBOD cannot provide
dependable performance and therefore may not allow a node to write to it quickly
enough. If a node is unable to write to a quorum disk device quickly enough, the
node is falsely evicted from a cluster.
2.10. Red Hat High Availabilit y Add-On and SELinux
The High Availability Add-On for Red Hat Enterprise Linux 6 supports SELinux in the enfo rci ng
state with the SELinux policy type set to targ eted .
Note
When using SELinux with the High Availability Add-On in a VM environment, you should
ensure that the SELinux boolean fenced _can_netwo rk_co nnect is persistently set to o n.
This allows the fence_xvm fencing agent to work properly, enabling the system to fence
virtual machines.
For more information about SELinux, refer to Deployment Guide for Red Hat Enterprise Linux 6.
2.11. Mult icast Addresses
The nodes in a cluster communicate among each other using multicast addresses. Therefore, each
network switch and associated networking equipment in the Red Hat High Availability Add-On must
be configured to enable multicast addresses and support IGMP (Internet Group Management
Protocol). Ensure that each network switch and associated networking equipment in the Red Hat
High Availability Add-On are capable of supporting multicast addresses and IGMP; if they are,
ensure that multicast addressing and IGMP are enabled. Without multicast and IGMP, not all nodes
can participate in a cluster, causing the cluster to fail; use UD P unicast in these environments, as
described in Section 2.12, “ UDP Unicast Traffic” .
Note
Procedures for configuring network switches and associated networking equipment vary
according each product. Refer to the appropriate vendor documentation or other information
about configuring network switches and associated networking equipment to enable multicast
addresses and IGMP.
2.12. UDP Unicast Traffic
As of the Red Hat Enterprise Linux 6.2 release, the nodes in a cluster can communicate with each
other using the UD P Unicast transport mechanism. It is recommended, however, that you use IP
multicasting for the cluster network. UDP unicast is an alternative that can be used when IP
multicasting is not available.
Red Hat Ent erprise Linux 6 Clust er Administ rat ion
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