Cluster Re-mastering and Fast re-configuring

RAC 11g R2

_gcs_file_to_lock ------ old lazy remastering (re-configure time locks/delete (Join/leave the node) the DLM in all instances then configure but in new Oracle version 11g below parameter.


_gcs_fast_reconfig, _lm_master_weight  Main Parameter to maintain.(GRD TC in 11g and JOIN/LEAVE node to re-distribute the resources.

The most common reasons for Re-mastering any Re-configuration.

1. when a node joins or leaves a cluster.

2. when an instance death is detected.Every instance updates the controlfile with a 

     heartbeat through its Checkpoint (CKPT) process. If heartbeat information is not 

     present for x amount of time (normally 30 seconds in UNIX variants), the instance is 

     considered to be dead and the Instance Membership Recovery (IMR) 

     process initiates reconfiguration.

3. Reconfiguration event is due to a communication failure.Communication channels are

     established between the Oracle processes across the nodes.

(GRD / CLUSTER Re-mastering and Re-configuring) 

GRD / CLUSTER re-mastering and re-configuring dynamically by LMON

Reconfigure process triggers IMR (Instance Membership Recovery), and Seven Steps process to ensures complete reconfiguration: -

1. The Name Service is Frozen.
2. IDLM is frozen.Lock Database is Frozen.
3. Determination of membership and validation and IMR occur.
4. Bitmap rebuild take place (GRD), including instance name.
5. Dead all instance
6. Unfreeze and release the name of services for use.
7. Hand over reconfiguration to GES/GCS.


IMR  starts and node eviction take place, let's look at the corresponding Messgaes in the ALERT.LOG and LMON trace files to get a better Picture.


(IMR is a Deep Level of Node Evection Process) Read IMR (instance Membership recovery) click : here