HP ProLiant 4500 Compaq ProLiant Cluster HA/F100 and HA/F200 Administrator Gui - Page 53

Enhanced High Availability Features of the HA/F200

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2-22 Compaq ProLiant Clusters HA/F100 and HA/F200 Administrator Guide Enhanced High Availability Features of the HA/F200 A "single point of failure" refers to any component in the system that, should it fail, prevents the system from functioning. Single points of failure in hardware can be minimized, and in some cases eliminated, by using redundant components. The most effective way of accomplishing this is by clustering. The Compaq ProLiant Cluster HA/F100 reduces the single points of failure that exist in a single-server environment by allowing two servers to share storage and take over for each other in the event that one server fails. The Compaq ProLiant Cluster HA/F200 goes one step further by implementing a dual redundant Fibre Channel Arbitrated Loop configuration. The Compaq ProLiant Cluster HA/F200 further enhances high availability through the use of additional, redundant, components in the server-to-storage connection and in the shared storage system itself. In the event of a failure, processing is switched to an alternate path without affecting applications and end users. In fact, this path switch is transparent even to the Windows NT file system (NTFS). The combination of multiple paths and redundant hardware components provided by the HA/F200 offers significantly enhanced high availability over non-redundant configurations. A single component failure in the HA/F200 will result in an automatic failover to an alternate component, allowing end users to continue accessing their applications without interruption. Some typical failures and associated responses in an HA/F200 configuration are: s A server failure will cause MSCS to fail application processing over to the second server. s A host bus adapter failure will cause I/O requests intended for the failed adapter to be re-routed through the remaining adapter. s A storage hub, or cable, failure will be treated like a host bus adapter failure and a failover to the second host bus adapter, which is using a different storage hub and cables, will occur. s An array controller failure will cause the redundant array controller to take over for the failed controller. In all of the above examples, end users will experience minimal interruptions while the failover occurs. In some cases, the interruptions may not even be noticeable.

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2-22
Compaq ProLiant Clusters HA/F100 and HA/F200 Administrator Guide
Enhanced High Availability Features of the HA/F200
A “single point of failure” refers to any component in the system that, should
it fail, prevents the system from functioning. Single points of failure in
hardware can be minimized, and in some cases eliminated, by using redundant
components. The most effective way of accomplishing this is by clustering.
The Compaq ProLiant Cluster HA/F100 reduces the single points of failure
that exist in a single-server environment by allowing two servers to share
storage and take over for each other in the event that one server fails. The
Compaq ProLiant Cluster HA/F200 goes one step further by implementing a
dual redundant Fibre Channel Arbitrated Loop configuration.
The Compaq ProLiant Cluster HA/F200 further enhances high availability
through the use of additional, redundant, components in the server-to-storage
connection and in the shared storage system itself. In the event of a failure,
processing is switched to an alternate path without affecting applications and
end users. In fact, this path switch is transparent even to the Windows NT file
system (NTFS). The combination of multiple paths and redundant hardware
components provided by the HA/F200 offers significantly enhanced high
availability over non-redundant configurations.
A single component failure in the HA/F200 will result in an automatic failover
to an alternate component, allowing end users to continue accessing their
applications without interruption. Some typical failures and associated
responses in an HA/F200 configuration are:
■
A server failure will cause MSCS to fail application processing over to
the second server.
■
A host bus adapter failure will cause I/O requests intended for the failed
adapter to be re-routed through the remaining adapter.
■
A storage hub, or cable, failure will be treated like a host bus adapter
failure and a failover to the second host bus adapter, which is using a
different storage hub and cables, will occur.
■
An array controller failure will cause the redundant array controller to
take over for the failed controller.
In all of the above examples, end users will experience minimal interruptions
while the failover occurs. In some cases, the interruptions may not even be
noticeable.