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Tuesday, March 29, 2016

ASM Background Processes

ASM Background Processes

An ASM instance comes with a few additional background processes that assist the ASM instance to perform its course of action. Therefore, understanding the individual role played by these ASM-specific background processes in order to know how they help the ASM instance to manage and carry out its functionality, will be helpful to DBAs. Here Iam going to cover the most useful ASM-specific background processes and the part played by the individual ASM-specific background processes:

RBAL - Rebalancer: It opens all the device files as part of disk discovery and coordinates the ARB processes for rebalance activity.

ARBx - Actual Rebalancer: They perform the actual rebalancing activities. The number of ARBx processes depends on the ASM_POWER_LIMIT init parameter.

ASMB - ASM Bridge: This process is used to provide information to and from the Cluster Synchronization Service (CSS) used by ASM to manage the disk resources. Responsible to communicate the database Instance to the ASM Instance, provides the heartbeat to the ASM instance.

ORBn - Rebalance ASM data extent movements. There can be many of this at the same time.

OSMB - (ASM) Any database instance that is using an ASM disk group will contain a background process called OSMB. The OSMB process is responsible for communicating with the ASM instance..Helps to manage the drive storage.

GMON - ASM Diskgroup monitor process, monitors all the mounted diskgroups and is responsible for maintaning consisten disk membership and status information

PZ9n - Parallel slave processes are used to fetch data from GV$ dynamic view in a cluster

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