HP XP P9000 for Compatible PAV Software Licenses - Manual (Page 7)

WLM in goal mode
The WLM must be in goal mode to support dynamic Parallel Access Volumes operations. The WLM
is in goal mode when the Dynamic alias management setting in the WLM Service Coefficient/Service
Definition Options dialog box is set to YES. While in goal mode, the WLM manages the system
to meet a performance goal.
WLM in compatibility mode
The WLM must be in compatibility mode to support static Parallel Access Volumes operations. The
WLM is in compatibility mode when the Dynamic alias management setting in the WLM Service
Coefficient/Service Definition Options dialog box is set to NO. While in compatibility mode, the
WLM manages the system according to parameters in IPS and ICS (IEAIPSxx and IEAICSxx parmlib
members).
Hyper Parallel Access Volumes
The Hyper Parallel Access Volumes feature allows you to assign alias devices to one base device,
but have all other base devices in the same CU share these aliases.
When using the Hyper Parallel Access Volumes feature, the number of alias devices assigned to
each base device does not need to change, as is required when using Parallel Access Volumes in
dynamic mode. With the Hyper Parallel Access Volumes feature, a whole collection of alias devices
can be mapped to one base device in a CU.
You can specify the PAV feature (Parallel Access Volumes or Hyper Parallel Access Volumes) to
use for each host computer. Therefore, an alias device may accept I/O requests issued through
Parallel Access Volumes or Hyper Parallel Access Volumes.
Flow of I/O requests 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 Parallel Access Volumes. 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 no alias devices are assigned to the device.
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