What are the Disadvantages of a CLUSTER?

Answer 1

Low performance in case of DML operations
Example: The EMPLOYEE and DEPARTMENT table share the DEPT_ID column. When you cluster the employees and departments tables, Oracle physically stores all rows for each department from both the tables.
Ex:
Step:1 Create a Cluster

Create CLUSTER c1(deptno number(2));

Step:2 Create a Employee table

Sql> Create table emp(empno number(4),  ename varchar2(15),  sal number(7),  deptno number(2)) cluster  c1(deptno);

Step:3 Create a Department table

  Sql> Create table dept(dname varchar2(15), deptno number(2),  loc varchar2(15)) cluster c1(deptno);

Step:4 Create a Index on Cluster

Sql> Create index id_c1 on cluster c1;

Answer 2

Disadvantages of clustering are complexity and inability to recover from database corruption.

In a clustered environment, the cluster uses the same IP address for Directory Server and Directory Proxy Server, regardless of which cluster node is actually running the service. That is, the IP address is transparent to the client application. In a replicated environment, each machine in the topology has its own IP address. In this case, Directory Proxy Server can be used to provide a single point of access to the directory topology. The replication topology is therefore effectively hidden from client applications. To increase this transparency, Directory Proxy Server can be configured to follow referrals and search references automatically. Directory Proxy Server also provides load balancing and the ability to switch to another machine when one fails.

Answer 3

Disadvantages of cluster SQL server

Expensive when compared to other alternatives of failover as stand-by servers and log shipping will cost you more.
Setup time is more when compared to other options.
Maintenance will be more when it is compared to other options.
You need to hire experienced network administrators and database administrators to handle the clustering.