HP XP7 Storage - Manual (Page 8)

I/O request workflow using Parallel Access Volumes
Multiple alias devices are assigned to a base device in a CU to enable the base device to handle
multiple I/O requests.
In the following figure, three alias devices are each assigned to base devices 1, 2 and 3.
As illustrated with the arrows in the figure, I/O requests converge on base device 1 when a host
computer accesses the device using PAV. Since alias devices A, B, and C were assigned to base
device 1 in advance of the operation, I/O requests are automatically issued to these alias devices.
Similarly, if a host computer accesses base devices 2 and 3, the I/O requests are automatically
issued to the alias devices assigned to those two base devices. Base device 4 is not able to process
multiple I/O requests since an alias device is not assigned to the device.
I/O request workflow using Hyper Parallel Access Volumes
Multiple alias devices are assigned to a base device in a CU to enable the base device to handle
multiple I/O requests. In HPAV, alias devices are pooled together in a single CU. All base devices
in the CU share alias devices.
In the following figure, three alias devices each are assigned to base devices 1, 2, and 3.
As illustrated with the arrows in the figure, I/O requests converge on base device 1 when a host
computer accesses the device using PAV. I/O requests are automatically issued to unused alias
devices among the nine alias devices in the CU.
Similarly, if a host computer accesses base devices 2, 3, and 4, the I/O requests are automatically
issued to unused alias devices among the nine alias devices. Base device 4 can process multiple
I/O requests even though an alias device is not specifically assigned to the device.
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