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Oracle Clusterware Provides infrastructure that binds multiple nodes
that then operate as single server. Clusterware monitors all components like
instances and listeners. There are two important components in Oracle
clusterware, Voting Disk and OCR (Oracle Cluster Registry).
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Voting
Disk is file that resides on shared storage and Manages cluster members.
Voting disk reassigns cluster ownership between the nodes in case of failure.
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OCR (Oracle Cluster Registry) Resides on shared storage and
maintains information about cluster configuration and information about cluster
database. OCR contains information like which database instances run on which
nodes and which services runs on which database.
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CRS Resource
Anything that Oracle Clusterware manages is classified as CRS resource like database,
instance, service, listener, VIP address and so on.
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Cluster-Aware Storage is storage solution for Oracle RAC like RAW device,OCFS, ASM.
Interconnect is private network that connects all the servers in cluster. Interconnect uses switch that only nodes in cluster can access. Instances in cluster communicate to each other via interconnect.
Cache Fusion – is disk less cache coherency mechanism in Oracle RAC that provides copies of data blocks directly from one instance’s memory cache (in which that block is available) to other instance (instance which is request for specific data block). Cache Fusion provides single buffer cache (for all instances in cluster) through interconnect.
Interconnect is private network that connects all the servers in cluster. Interconnect uses switch that only nodes in cluster can access. Instances in cluster communicate to each other via interconnect.
Cache Fusion – is disk less cache coherency mechanism in Oracle RAC that provides copies of data blocks directly from one instance’s memory cache (in which that block is available) to other instance (instance which is request for specific data block). Cache Fusion provides single buffer cache (for all instances in cluster) through interconnect.
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In Single Node oracle database, an
instance looking for data block first checks in cache, if block is not in cache
then goes to disk to pull block from disk to cache and return block to client.
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In RAC Database there is remote cache so instance should look not only in local cache
(cache local to instance) but on remote cache (cache on remote instance). If
cache is available in local cache then it should return data block from local
cache; if data block is not in local cache, instead of going to disk it should first go to remote cache (remote
instance) to check if block is available in local cache (via interconnect)
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SSH User Equivalency – means assigning same properties (username, userid,group, group id and same password) to operating system
user (installing & owning RAC database) across all nodes in cluster
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CVU (Cluster Varification Utility) – is utility to verify that
system meets all the criteria for Oracle Clusterware Installation.
