STRASPBAL (Start ASP Balance)

STRASPBAL Command syntax diagram

 

Purpose

The Start ASP Balance (STRASPBAL) command allows the user to start the auxiliary storage pool (ASP) balancing function for one or more auxiliary storage pools (ASPs). Four types of ASP balancing can be started:>

1. Capacity balancing - The data on all the units within the ASP will be balanced so each unit has an equal percentage of used and unused space. This is useful when new units are added to an ASP. Instead of having several units with the majority of the data and several new ones with no data, the user can spread the data evenly across all the units.
2. Usage balancing - The high-use and low-use data on each unit in the ASP is redistributed to balance the arm utilization of each unit within the specified ASP. *USAGE balancing cannot be done until the trace controlled by the Trace ASP Balance (TRCASPBAL) command has collected usage statistics. TRCASPBAL starts the trace function that will identify the high-use and low-use data on each unit. This information will be used when the Start ASP Balance (STRASPBAL) TYPE(*USAGE) command is run. After this balance activity has run to completion the trace information will be cleared. Usage balancing is useful when the ASP contains large capacity disk units.
3. Hierarchical Storage Management balancing - The high-use and low-use data on each unit in the ASP is redistributed so that the high-use data resides on high performance units and the low-use data resides on low performance units. The ASP being balanced in this manner must contain the correct mixture of slow and fast units to perform this type of balance. This allows the low-use data on the high performance units to be moved to low performance units. Data that is high-use that resides on slow units will be moved to the fast disk units. *HSM balancing cannot be done until the trace controlled by the Trace ASP Balance (TRCASPBAL) command has collected usage statistics. TRCASPBAL starts the trace function that will identify the high-use and low-use data on each unit. This information will be used when the Start ASP Balance (STRASPBAL) TYPE(*HSM) command is run. After this balance activity has run to completion the trace information will be cleared. *HSM balancing is useful when the ASP contains compressed disk units.
4. Move data from units - This option can be used to reduce the down time associated with removing a disk unit. A unit that is scheduled for removal can be marked to end allocations by specifying UNIT(unit-number) and TYPE(*ENDALC). This will keep new allocations away from this unit. For all units marked *ENDALC, specifying TYPE(*MOVDTA) will move data from the marked units to other units in the same ASP. To resume allocations for units marked *ENDALC, specify UNIT(unit-number) and TYPE(*RSMALC). New allocations will once again be allowed to this unit. The Check ASP Balance (CHKASPBAL) command can be used to determine which units are currently marked *ENDALC.>

The user may specify a time limit that the function is to run for each ASP being balanced or the balance can be set to run to completion. If the balance function needs to be ended, use the End ASP Balance (ENDASPBAL) command. A message will be sent to the system history (QHST) log when the balancing function is started for each ASP. A message will also be sent to the QHST log when the balancing function completes or is ended.

If the balance function is run for a few hours and then stopped, it will continue from where it left off when the balance function restarts. This allows the balancing to be run during off hours over a several day period.

For more information about ASP balancing see the Hierarchical Storage Management

book.

Restrictions: You must have *ALLOBJ special authority to use this command.

 

Required Parameters

TYPE

Specifies the type of auxiliary storage pool (ASP) balancing that is to be done.

*CAPACITY: The capacity balance function will be started for the specified ASP (ASP or ASPDEV parameter).

*USAGE: The usage balance function will be started for the specified ASP (ASP or ASPDEV parameter).

*HSM: The hierarchical storage management balance function will be started for the specified ASP (ASP or ASPDEV parameter).

*MOVDTA: Data will be moved off all units marked *ENDALC to other units in the same ASP. The CHKASPBAL command can be used to determine which units are marked *ENDALC.

*ENDALC: New allocations will no longer go to the specified units (UNIT parameter). However, the system will use these units for new allocations to avoid 'Out of storage' conditions.

*RSMALC: Resume allocations to the specified units (UNIT parameter). If the unit has a much lower percentage used than other units in the ASP, run STRASPBAL again specifying TYPE(*CAPACITY) for the ASP that contains the unit. This will keep new allocations balanced across the units in the ASP, instead of going mostly to this unit.

 

Optional Parameters

ASP

Specifies the auxiliary storage pool (ASP) for which the ASP balancing function is to be started.

*ALL: ASP balancing will be started for the system ASP (ASP number 1) and all basic ASPs (ASP numbers 2-32) defined to the system.

auxiliary-storage-pool-number: Specify the ASP for which ASP balancing is to be started. Valid ASP numbers are 1 to 32. Up to 32 ASP numbers may be specified.

ASPDEV

Specifies the name of the auxiliary storage pool (ASP) device for which the ASP balancing is to be started.

*ALLAVL: ASP balancing will be started for all ASP devices that currently have a status of 'Available'.

auxiliary-storage-device-name: Specify the name of the independent ASP device for which ASP balancing is to be started. Up to 32 ASP device names may be specified.

UNIT

Specifies the unit number for which new allocations are to be ended (*ENDALC) or for which new allocations are to resume (*RSMALC). Specifying TYPE(*MOVDTA) will start moving data off the units marked *ENDALC.

unit-number: Specify the unit number for which new allocations are to end (*ENDALC) or resume (*RSMALC). Up to 300 unit numbers may be specified.>

TIMLMT

Specifies the amount of time, in minutes, that the ASP balancing function will be allowed to run. When the time limit is reached the function will end. For example, if ASP(*ALL) is specified and the machine has four ASPs configured and TIMLMT(60) is specified, four balance functions are started and each can run 60 minutes. If the balancing of any ASP has not completed after 60 minutes, it will be forced to end. This allows you to do ASP balancing incrementally. The balance function will not run across an IPL.

*NOMAX: There is no time limit for the balance function. For a large ASP the balance function can take a long time to complete. If you start the balance function with *NOMAX and you want to force the function to end, you can use the End ASP Balance (ENDASPBAL) command.

time-limit: Specify the time limit that the balance function will be allowed to run. Valid values range from 1 to 9999 minutes.

Examples for STRASPBAL

Example 1: Starting ASP Balancing for ASP 1

STRASPBAL  ASP(1) TIMLMT(*NOMAX) TYPE(*CAPACITY)

This command starts the *CAPACITY ASP balance function for ASP 1. The balance function will run until the capacity for each of the units has been balanced.

Example 2: Starting ASP Balancing with a Time Limit

STRASPBAL  ASP(*ALL) TIMLMT(60) TYPE(*USAGE)

This command starts the *USAGE ASP balance function for the system ASP and each configured basic ASP for which the TRCASPBAL command has been run. Each balance function will have a time limit of sixty minutes. After sixty minutes, any balance functions which have not completed will be ended.

Example 3: Starting ASP Balancing for an ASP Device

STRASPBAL  ASPDEV(MYASP1) TIMLMT(*NOMAX) TYPE(*CAPACITY)

This command starts the *CAPACITY ASP balance function for the ASP device named MYASP1. The balance function will run until complete.

Example 4: Preparing to Remove Units

STRASPBAL  UNIT(11 12 13) TYPE(*ENDALC)

STRASPBAL  TYPE(*MOVDTA)

The first STRASPBAL command marks units 11, 12 and 13 to no longer receive new allocations. The second STRASPBAL command begins to move data off the marked units. It is recommended that the *MOVDTA ASP balancing function be done during an off-peak time.

Error messages for STRASPBAL

*ESCAPE Messages

CPF18AB

ASP balancing for ASP &2 already started.

CPF18AD

ASP &2 must contain more than a single unit.

CPF18AE

ASP &2 does not contain trace data.

CPF18AF

ASP &2 does not contain mixed unit types.

CPF18B1

Trace function currently running for ASP &2.

CPF18B3

Balance type not valid for ASP &2.