HP Storage Mirroring V5 Software - Manual (Page 123)

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X Failover
Failover
Failover is the process in which a target stands in for a failed source. As a result, user and application requests that are directed
to the failed source are routed to the target.
Storage Mirroring monitors the source status by tracking network requests and responses exchanged between the source
and target. When a monitored source misses a user-defined number of requests, Storage Mirroring assumes that the machine
has failed. Storage Mirroring then prompts the network administrator to initiate failover, or, if configured, it occurs
automatically.
The failover target assumes the network identity of the failed source. When the target assumes the identity of the source,
user and application requests destined for the source machine or its IP address(es) are routed to the target.
When partnered with the Storage Mirroring data replication capabilities, failover routes user and application requests with
minimal disruption and little or no data loss. In some cases, failover may be used without data replication to ensure high
availability on a machine that only provides processing services, such as a web server.
Failover can be configured to stand in for one or more IP addresses associated with different NICs on the source. Each IP
address can be added to a specific target NIC making NIC configuration very flexible. For example, a single NIC on the source
may have one or more IP addresses assigned to it. If that source or the NIC fails, all traffic from the source is directed to the
target. If there are multiple NICs on the source, the target can assume the traffic from all of the addresses. Additional NICs
on the target increase flexibility and control. Secondary target NICs can assume the traffic from a failed source NIC while
normal target traffic can continue to use the primary target NIC.