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If you add the new units and choose to spread data, IBM i automatically migrates data from
the existing disks onto the new logical units.
You can then use the STRASPBAL TYPE(*ENDALC) IBM i command to mark the units to remove
from the configuration, as shown in Figure 11-40. This command can help reduce the
downtime associated with removing a disk unit and keeps new allocations away from the
marked units.
Start ASP Balance (STRASPBAL)
Type choices, press Enter.
Balance type . . . . . . . . . . > *ENDALC
Storage unit . . . . . . . . . .
+ for more values
F3=Exit F4=Prompt
F24=More keys
F5=Refresh
F12=Cancel
*CAPACITY, *USAGE, *HSM...
1-4094
Bottom
F13=How to use this display
Figure 11-40 Ending allocation for existing disk units
When you later run the STRASPBAL TYPE(*MOVDTA) IBM i command, all data is moved
from the marked units to other units in the same ASP, as shown in Figure 11-41. You must
have sufficient new capacity to allow the data to be migrated.
Start ASP Balance (STRASPBAL)
Type choices, press Enter.
Balance type . . . . . . . . . . > *MOVDTA
Time limit . . . . . . . . . . .
F3=Exit F4=Prompt
F24=More keys
F5=Refresh
F12=Cancel
*CAPACITY, *USAGE, *HSM...
1-9999 minutes, *NOMAX
Bottom
F13=How to use this display
Figure 11-41 Moving data from units marked *ENDALC
You can 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 you must end the balance function prior to this, use
the End ASP Balance (ENDASPBAL) command. A message is sent to the system history
(QHST) log when the balancing function is started for each ASP. A message is also 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 continues from where it left off when the balance
function restarts so that the balancing can be run during off-hours over several days.
To remove the old units from the configuration, you must use DST and reload the system or
partition with IPL. With this method, you can remove the existing storage units over a period
of time. This method requires that both the old and new units are attached to the system at
the same time. Therefore, additional IOPs and IOAs might be required if you are migrating
from an ESS to a DS8000. It might be possible in your environment to reallocate logical
volumes to other IOAs, but careful planning and implementation are required.
Chapter 11. IBM i considerations
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