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in RAC by ACE (20,920 points)

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by ACE (20,920 points)
LMSn
    Lock Manager Server process - GCS     

this is the cache fusion part and the most active process, it handles the consistent copies of blocks that are transferred between instances. It receives requests from LMD to perform lock requests. I rolls back any uncommitted transactions. There can be up to ten LMS processes running and can be started dynamically if demand requires it.

they manage lock manager service requests for GCS resources and send them to a service queue to be handled by the LMSn process. It also handles global deadlock detection and monitors for lock conversion timeouts.

as a performance gain you can increase this process priority to make sure CPU starvation does not occur

you can see the statistics of this daemon by looking at the view X$KJMSDP

LMON
    Lock Monitor Process - GES     

this process manages the GES, it maintains consistency of GCS memory structure in case of process death. It is also responsible for cluster reconfiguration and locks reconfiguration (node joining or leaving), it checks for instance deaths and listens for local messaging.

A detailed log file is created that tracks any reconfigurations that have happened.

LMD
    Lock Manager Daemon - GES     

this manages the enqueue manager service requests for the GCS. It also handles deadlock detention and remote resource requests from other instances.

you can see the statistics of this daemon by looking at the view X$KJMDDP

LCK0
    Lock Process - GES     manages instance resource requests and cross-instance call operations for shared resources. It builds a list of invalid lock elements and validates lock elements during recovery.

DIAG
    Diagnostic Daemon     This is a lightweight process, it uses the DIAG framework to monitor the health of the cluster. It captures information for later diagnosis in the event of failures. It will perform any necessary recovery if an operational hang is detected.
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