Thursday, June 26, 2008

New Background Processes In 11g

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Here are the new background processes in 11g :-

ACMS (atomic control file to memory service) per-instance process is an agent that contributes to ensuring a distributed SGA memory update is either globally committed on success or globally aborted in the event of a failure in an Oracle RAC environment.

DBRM (database resource manager) process is responsible for setting resource plans and other resource manager related tasks.

* DIA0 (diagnosability process 0) (only 0 is currently being used) is responsible for hang detection and deadlock resolution.

DIAG (diagnosability) process performs diagnostic dumps and executes global oradebug commands.

EMNC (event monitor coordinator) is the background server process used for database event management and notifications.

FBDA (flashback data archiver process) archives the historical rows of tracked tables into flashback data archives. Tracked tables are tables which are enabled for flashback archive. When a transaction containing DML on a tracked table commits, this process stores the pre-image of the rows into the flashback archive. It also keeps metadata on the current rows.

FBDA is also responsible for automatically managing the flashback data archive for space, organization, and retention and keeps track of how far the archiving of tracked transactions has occurred.

GTX0-j (global transaction) processes provide transparent support for XA global transactions in an Oracle RAC environment. The database autotunes the number of these processes based on the workload of XA global transactions. Global transaction processes are only seen in an Oracle RAC environment.

KATE performs proxy I/O to an ASM metafile when a disk goes offline.

MARK marks ASM allocation units as stale following a missed write to an offline disk.

SMCO (space management coordinator) process coordinates the execution of various space management related tasks, such as proactive space allocation and space reclamation. It dynamically spawns slave processes (Wnnn) to implement the task.

VKTM (virtual keeper of time) is responsible for providing a wall-clock time (updated every second) and reference-time counter (updated every 20 ms and available only when running at elevated priority).

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