Compaq 112726-001 - ProLiant - 6500 Administrator's Manual page 79

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MA8000/EMA12000 Storage Subsystems, each of which holds up to
72 disk drives.
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Two dual-port HSG80 Array Controllers installed in each storage
subsystem's controller enclosure.
NOTE: For more information about redundant Fibre Channel Arbitrated Loops (FC-ALs) in
a PDC/O5000, see Chapter 2, "Cluster Architecture."
The Storage Hubs are available in two models:
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Storage Hub 7 (7 ports)
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Storage Hub 12 (12 ports)
To determine which Storage Hub model is appropriate for a redundant FC-AL
in your cluster, you need to know the following:
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Whether you are implementing dual redundancy or quad redundancy in
the redundant FC-AL. Dual redundancy requires two host adapters per
node and two Storage Hubs. Quad redundancy requires four host
adapters per node and four Storage Hubs.
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Total number of host adapters in all nodes
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Total number of array controller ports in all of the storage subsystems in
the redundant FC-AL
You will need enough Storage Hub ports to accommodate the connections
from the host adapters to the Storage Hubs and from the Storage Hubs to the
array controllers.
The number of storage subsystems and shared disk drives used in a
PDC/O5000 redundant FC-AL depends on the amount of shared storage space
required by the database, the hardware RAID levels used on the shared storage
disks, and the number and storage capacity of disk drives installed in the
enclosures. Refer to "Raw Data Storage and Database Size" in this chapter for
more details.
NOTE: For improved I/O performance and cluster integrity, as you increase the number of
nodes in a PDC/O5000, you should also increase the aggregate bandwidth of the shared
storage subsystem by adding more or higher-capacity disk drives.
Cluster Planning 4-5