OracleRACDRM Basic Concepts

In oracleRAC, each instance has a data cache pool, and each block change coordinates resources between instances to maximize performance, thus ensuring data integrity.

In oracle RAC, each instance has a data cache pool, and each block change coordinates resources between instances to maximize performance, thus ensuring data integrity.

In Oracle RAC, each instance has a data cache pool. Each block change coordinates resources between instances to maximize performance and ensure data integrity.

In a RAC cluster, each cached data copy, also called a cache resource, has an instance called a master node.

In 10.1.0.2, once a cache resource is master,

The re-remaster of the cache resources or the automatic change of the master node only happens to the normal start and stop of the RAC instance node or abnormal problems between cluster management resources.

That is to say, if node B is a master NODE of the cache resource, the resource will be reconfigured from master to node B until the RAC NODE is reconfigured.

The introduction of a new Resource remaster concept in oracle 10 Gb is called DRM (Dynamic Resource management [ID 390483.1]). Through DRM, the RAC instance node is reconfigured.

It is no longer A factor for cache resources to be remaster. If cache resources are frequently accessed by node a, A resource can be remaster from node B to NODE.

Other concepts are as follows:

In 10gR1 DRM is driven by affinity of files and in 10gR2 it is based on objects.

DRM attributes are intentionally uninitialized ented since they may change depending on the version. These attributes shoshould not be changed without discussing with Support.

Two instance will not start a DRM operation at the same time however lmd, lms, lmon processes from all instances collectively take part in the DRM operation.

Normal activity on the database is not affected due to DRM. This means users continue insert/update/delete operations without any interruptions. Also DRM operations complete very quickly.

DRM login cause "latch: cache buffers chains" and "latch: object queue header operation" wait event, you can go throught this way to disable DRM:

_ Gc_affinity_time = 0

_ Gc_undo_affinity = FALSE

Also, you can used another two implicit parameters dynamic change

_ Gc_affinity_limit = 10000000

_ Gc_affinity_minimum = 10000000

The value above can be changed according to actual requirements.