Database Reference
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Figure 12-3. HBA-to-port mappings
When increasing the number of nodes and servers accessing the storage subsystem, seldom is any consideration
given to the number of interfaces to the storage subsystem and the capacity of the I/O path. Care should be given
to ensuring that the number of HBAs is equal to the number of disk controllers. Using the disk controller slots to
accommodate more disk arrays could have a negative impact on the total throughput of the I/O subsystem.
For example, on a 16-port Fiber Channel switch, the ideal configuration would be to have 8 HBAs and 8 disk
controller ports, giving a total throughput of 8 ´ 200MB 4 = 1.6 GB/sec. However, if the number of HBAs is reduced to 4
to provide room for additional storage, then the total throughput drops down by 50% (4 ´ 200 MB = 800MB/sec).
The number of controllers that is mapped to an HBA device determines the speed of the write operation. How
many controllers an HBA device can map also depends on the queue depth of the HBA devices.
4 Assuming the maximum theoretical payload of 2GB/sec, Fiber Channel is 200MB/sec. Source: Oracle Corporation.
 
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