XP10000 (HITA737-96003, March 2007)

12 HPAV for the XP1024/XP128/XP12000/XP10000

Support for Dynamic Alias Management by the Workload Manager (WLM) is dependent on the following

three parameter settings:

• WLM Goal Mode setting

• WLM “Dynamic alias management” setting in the Service Coefficients/Service Definitions window (see

page 41)

• WLMPAV setting of each base device as defined in the “Define Device Parameters / Features” HCD

definition window (see page 36)

Static and Dynamic HPAV Operations

Static or dynamic HPAV operation is determined by the combination of the following parameter settings:

• The ‘WLMPAV=xxx’ parameter setting for each device defined to the z/OS and OS/390 host through

the HCD. The default setting of this parameter is ‘WLMPAV=YES’ for 3390B or 3390A devices defined

through the HCD.

• The ‘Dynamic Alias Support’ parameter setting for WLM.

• Static HPAV is implemented when the WLM feature for ‘Dynamic Alias Support’ is set to NO and the

appropriate aliases are assigned to the base devices using Command View XP or XP Remote Web

Console. The setting of the ‘WLMPAV=xxx’ parameter defined for each 3390B or 3390A device is

ignored. In addition, the ‘I/O Priority Management’ setting for WLM is ignored (see Table 2).

• Dynamic HPAV is implemented when ‘Dynamic Alias Support’ is set to YES and the appropriate aliases

are assigned to the base devices using Command View XP or XP Remote Web Console. The setting of

the ‘WLMPAV=xxx’ parameter defined for each 3390B or 3390A device must be set to ‘YES’ if WLM is

to manage the alias device address assignments. In addition, the ‘I/O Priority Management’ setting for

WLM determines the dynamic alias algorithm to be used for meeting the Performance Index of the

workloads under the control of WLM using the HPAV feature (see Table 2).

NOTE: When ‘Dynamic Alias Support’ is enabled, the alias-to-base assignments are managed by the

WLM component of the z/OS and OS/390 system as needed in response to changes in I/O activity.

Static HPAV

When static HPAV is used, the number of aliases specified for each base device does not change, even

when the number of I/O requests to each device changes. When dynamic HPAV is used, the number of

aliases for each base device is likely to change as the number of I/O requests changes.

The following figure shows an example of static HPAV operations. Each of the three base devices (x10, x11,

and x12) has two aliases assigned. If I/O requests converge on base device x10 (shown by the large

arrow), the number of aliases for each base device remains unchanged.

Table 2 HCD settings for static and dynamic HPAV

Dynamic Alias Support I/O Priority Management Dynamic Alias Algorithm in Effect

NO NO None (static HPAV only)

NO YES None (static HPAV only)

YES NO Efficiency only

YES YES Both efficiency and goal