Types of Clusters

Types of Clusters:

1.       Operating system level

2.       Hardware level

3.       Network level

4.       Application level

a.        Failover cluster

b.       Parallel cluster

c.        Hybrid cluster

Failover Cluster:

Ex: VCS (VERITAS Cluster System)

Disadvantages of failover cluster:

1.       More downtime for the users
2.       No load balancing
3.       Wastage of resources
4.       Max it support 2 node cluster setup

Parallel cluster or scalable high performance cluster:

In 9i, it supports 67 nodes per cluster

In 10g, it supports 100 nodes per cluster

In 11g, it supports 100+ nodes per cluster

Advantages:

1.       Zero or negligible downtime for the users
2.       Better load balancing
3.       No wastage of resources
4.       It supports multiple nodes per cluster
5.       Best example oracle RAC

Hybrid Cluster:

It is a combination for both parallel & failover cluster

Ex: Data guard in RAC environment

Types of Cluster Software:

Types		Vendor
1.       Hp Service Guard 2.       Sun Cluster	Kernel level	HP Oracle SUN
3.       VERITAS cluster (failover + parallel) 4.       Oracle RAC (Truly Parallel)	User / Application level	Symantec Oracle

Real Application Cluster - RAC

Global cache is maintained by

1.       In 8i, OPS (Oracle parallel Server)

2.       From 9i, it is maintained by GRD (Global Resource directory)

Global Resource directory (GRD) = Global cache service (GCS) + Global Enqueue Services (GES)

                                                GRD = GCS + GES

RAC is not software; it is a concept in which multiple instances (each on separate node) and can access a common (single) database

Advantages of RAC:

1.       It offers SPAM

a.        S à Scalability

b.       Pà Performance

c.        Aà Availability

d.       Mà Manageability

2.       It Supports HA (high availability) operations to the services like VIPs, Scan IPs etc

3.       Automatic error Detection

4.       Automatic restart of failed services

5.       It supports TAF – Transparent Application Failover

Cluster Component:

1.       Clusterware Software
2.       Private Interconnect
3.       Shared Storage

Clusterware software:

It coordinates and manages all the cluster nodes of a cluster by treating all the nodes as a single large logical server

Version	Name of Cluster S/W
9i	Oracle cluster manager (Supports only Linux/windows)
10.1	Oracle CRS (cluster ready Service) a.        Supports all the o/s b.       Mandatory for building 10g RAC Setup
10.2	Oracle CRS is renamed to ORACLE CLUSTERWARE a.        Supports HA operations b.       High performance
11.2	a.        Grid Infrastructure b.       Combination of Clusterware binaries and ASM binaries

Oracle Homes

10.1	ASM_HOME (ASM) CRS_HOME (Clusterware) ORACLE_HOME (RDBMS)
10.2	CRS_HOME ORACLE_HOME (Clusterware + ASM)
11.2	GRID_HOME (Clusterware + ASM) ORACLE_HOME (RDBMS)