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ProLiant Cluster for NetWare 4.2
Administration
Outlined below are some helpful guidelines to assist you in administering and supporting the
ProLiant Cluster for NetWare 4.2.
Increasing Availability
Intra-cluster Communication
Should the servers experience a disruption in intra-cluster communication, they will initiate the
failover process. Obviously, this condition is only acceptable in the event of an actual failure that
disrupts the server’s ability to service client requests. Therefore, the reliability of the connections
between the servers in the cluster is a direct measure of the clustered system’s ability to maintain
costandby operation, wherein both servers are fully operational.
There are several ways to reduce the possibility of a disruption of intra-cluster communication.
Each method shares an underlying objective: to create redundant paths over which monitoring
will continue if the another path is disrupted. The ProLiant Cluster for NetWare 4.2 provides this
redundancy through the three lines of communication between servers: the NetWare link, the
optional dedicated link, and the disk link.
Compaq extends this redundancy with a feature that configures two Compaq Ethernet adapters or
two ports on a single adapter, such that one is a hot backup for the other. This feature, called
Advanced Network Fault Detection and Correction, is available on all Compaq 10/100 Fast
Ethernet products. This feature reduces the possibility of downtime due to network failure by
allowing the administrator to configure a redundant interconnect for each communication path.
In a redundant interconnect configuration, each communication path is configured with a primary
link and a backup link. If a component in the primary link fails, communication continues over
the backup link. The redundant interconnect feature significantly enhances the availability of
clustered systems.
Quorum Arbitration
Each server uses quorum arbitration to monitor and verify that the other server is operational. By
monitoring the other server’s usage of a reserved region on the shared volumes, both servers can
be sure that the other is still accessing the storage array. In the event that a server does not update
the information in this shared region, the cluster becomes aware of a potential failure. In order to
prevent false failovers, NHAS will verify the disk link status 4 times. If after the fourth
verification, or roughly 20 seconds, Server B has not accessed the reserved region of the disk,
Server A will set the disk link status to disconnected. If the NetWare link (and dedicated link, if
implemented) status is also disconnected, NHAS will initiate a failover to Server A.
IP and Applications Failover
Configuration
If you want your IP-based applications to failover to the other server when their host server fails,
you must set up your ProLiant Cluster for NetWare 4.2 to redirect all IP traffic from the failed
