Monday, June 15, 2009

Oracle 10G new background processes

With 10g many new background processes were introduced.
This note highlights those.


Memory Manager (MMAN) coordinates the sizing of different memory components within SGA. MMAN keeps a track of sizes of components and allocates/de-allocates memory based on their usage. This process is used only when you enable Automatic Shared Memory Management.


Process responsible for writing flashback logs which stores pre-image of data-blocks.

These logs can be used to flash back database to past point in time. It proves very handy specially in situation of logical data corruptions like an accidental drop/truncate of a table or commit of an unwanted transaction.


Change Tracking Writer (CTWR) Process introduced in 10g to track changes to block to assist fast RMAN incremental backups.


The Memory Monitor Light (MMNL) process introduced in 10g is responsible for writing out statistics buffer to disk as needed. It works with Automatic Workload Repository (AWR)


The memory monitor (MMON) process was introduced in 10g is responsible for gathering statistics for Automatic Workload Repository. This helps Oracle doing automatic problem detection and self tuning.


MMON background slave (m000) processes.


RBAL (Re-balancer) is the ASM related process that performs rebalancing of disk resources controlled by ASM.


These processes are managed by the RBAL process and are used to do the actual rebalancing of ASM controlled disk resources. The number of ARBx processes invoked is directly influenced by the asm_power_limit parameter.


The ASMB process is used to provide information to and from the Cluster Synchronization Services used by ASM to manage the disk resources. It is also used to update statistics and provide a heartbeat mechanism.

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I am an Oracle Certified Professional, Oracle 9i/10G DBA, having 4+ years of core DBA experience.