DIFFERENCE BETWEEN ASM FAST MIRROR RESYNC AND ASM REBALANCE

Oracle ASM fast resync is used to the track the changes of extents during disk issue from an offline disk. OAFR keep the information until the disk is brought back online and sync all the extents during failure.

Whenever there is an issue with disk, the disk should be replaced in order to continue operation. Restoring from a failed disk to redundant failure group

Oracle ASM rebalance is an online activity which redistribute the data evenly across all the disk of diskgroup. Only one diskgroup can be rebalanced at a time using oracle ASM.

During addition or removal , asm has to rebalance the data across the diskgroup. During this process, the following occur

  • RBAL process create a rebalance plan and coordinate with redistribution
  • ARBn process spawns multiple slave process to work on the rebalance with the parameter asm_power_limit
  • The metadata will be updated to perform rebalance
  • The extents are allocated to each ARBn process like ARB1,ARB2,ARB3 ……
  • ARBn performs rebalance by locking the extents,relocating it and unlocking it

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