Oracle ASM disk resync allows multiple disks to be brought online simultaneously or to otherwise control the speed of the resync operation. Oracle ASM disk resync now has a Resync Power Limit to control resync parallelism and, therefore, improve performance. Disk Resync Checkpoint allows for faster recovery from instance failures by allowing the resync to resume from where it was interrupted or stopped instead of starting from the beginning.
This enhancement provides faster recovery from instance failure and faster resync performance overall.
Prior to specify the degree of parallelism only when the rebalance, you can now re-online disk when specified degree of parallelism to speed up the online speed, and can also view by querying v $ asm_operation to see the approximate time required. Disk synchronization checkpoint is to speed up the synchronization speed, for example, you are in online disk when suddenly closed the window, so if the version prior to 12c and you can only re online. Then, in 12c, Oracle will be the online process automatically creates a synchronous checkpoint, even if the window is closed, then re-synchronization will start from the latest checkpoint, it is clear that this greatly accelerate the speed of synchronization.
grammar:
alter diskgroup DATA online disk DATA001 power 4; --范围(0--1024)
View sync Estimated time remaining:
Select est_minutes from v$asm_operation;
Reference document:
http://docs.oracle.com/database/121/SQLRF/statements_1009.htm#BABEFCHE
http://docs.oracle.com/database/121/OSTMG/GUID-6BB31112-8687-4C1E-AF14- D94FFCDA736F.htm # OSTMG10070