HP XP7 Storage - Manual (Page 11)

3 Defining devices
This topic contains information on selecting base and alias device ratios and procedures on how
to use the hardware configuration definition (HCD) software application to define the mapping of
devices to LCUs that you have defined to the Remote Web Console host storage systems.
Unused device addresses usage as alias devices
You can use unused device addresses in CU as an alias for base devices. An optimum base-to-alias
device ratio ensures maximum efficiency in processing I/O requests.
Optimal Parallel Access Volumes results and base-to-alias device ratios
Use a base-to-alias device ratio of 1:3 for optimal results.
NOTE: The device ratio can vary based on how often a base device is accessed by the host
system.
For example, if you define all 256 devices of a CU to the host system, 64 base devices and 192
alias devices would exist. Three alias devices would be assigned to each base device.
Optimal dynamic PAV results and alias devices
To produce optimal results in dynamic PAV operations, create eight to 16 alias devices in each
CU.
NOTE: If multiple host systems access devices, you can get below optimal results. In this case,
use Multiple Allegiance (MA) host software.
Hyper Parallel Access Volumes optimum base/alias device ratio
For HPAV, to produce adequate results, assign eight to 16 alias devices to a PAV base device in
each CU, but not more than three alias devices to a single PAV base device.
Keep the number of alias devices assigned to each base device in a CU as equal as possible. For
example, you can assign 10 alias devices with three aliases each assigned to the first in a CU,
second and third base device, one alias assigned to the fourth base device, and no alias
assignments to the remaining base devices. Alternatively, you can assign one alias to each of the
10 addresses.
Defining logical control units to the Remote Web Console host storage
system
Before you can define LCUs to the Remote Web Console host storage system, define the channel
paths. Use the HCD to define logical control units (LCUs) and PAV devices to the Remote Web
Console host storage system.
You can use the HCD main screen to modify and view configuration data.
1.
From the ISPF/PDF primary options menu, select the HCD option.
2. On the HCD main screen, for I/O definition file, for Work I/O definition file (IODF), verify the
file is the one you want to use and then select option 1.
HP Confidential Unused device addresses usage as alias devices 11