askMLabs

Recently we resolved a  JDBC connection issue with RAC database.  I will detail the issue in 8 steps

My Env setup :
We have 11gR2 RAC database running using ASM storage and all the servers are in network domain domain1. Client is using one JAVA application and it is running on non-RAC 11g database and the servers are in a different network domain domain2.
Our task :
Our task is to migrate the database that the JAVA applications is using to the RAC setup on ASM storage and establish the JAVA applications to connect to the newly migrated database. The big challenge we faced here is due to the reason that the setups are in different domains. We are using the 11gR2 SCAN concept,which complicated the issue even more.
What we did :
I am giving here the outlined view of the migration plan, but we should consider many other things in the actual migration process.

1. export database from source
2. Move the dump files to target database node.
3. prepare the target database for import
4. import the database to target database
5. run utlrp to compile all the objects
6. Verify the errors from import logfile
7. "Note invalids,objects and schema status"
8. Compare the objects status with the source
9. verify the db links on target

All went fine. We tested the database connection from the server where java applications are running. We tested TOAD connection as well. All is well. We requested client to test the application after providing the JDBC connection string.

What is the issue :
Client raised an issue that the application is not able to connect to the database.

Troubleshooting:
As i said earlier, we tested TOAD connection. We tested sqlplus connection to the database. Both are working fine with the provided connecting string. Then we tried to dig into the SCAN listener concepts suspecting it might be an issue and configured everything as per the oracle documents. Finally we concluded that it is the issue only with JDBC connections.

Issue resolution :
Then prepared a java script to test the database java connections. Modified various settings on the database side and tested JDBC connection. Atlast we found the issue. The issue is with the connection string domain name specification.

How to test a Java Connection to oracle:
Pls see the video demo


Explanation:
As i said in my first sentence that the source and target environments are working in different domains, being source using domain2 and target using domain1. SCAN in domain1(RAC side) resolves to three IPs and the same is configured in the other network using NATing. Now the scan name resolves to three IPs in both source and target and they are connected with NATing. The host name in the connectiong string be the same as the init.ora parameter remote_listener and it should also match to the SCAN name. We should not include any domain names with SCAN name , remote_listername and with HOST setting in connecting string.

On Source RAC side:
The HOST=scan-cluster should exactly match the remote_listener parameter in the database.
SQL> show parameter remote_list
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
remote_listener                      string      scan-cluster:1521
On Applications Side: 
<database name="defaultOracle"
debug="false"
password="xxxxxxxxxxxxxxxx"
connectString="jdbc:oracle:thin:@(DESCRIPTION=(LOAD_BALANCE=on)(ADDRESS=(PROTOCOL=TCP)(HOST=scan-cluster) (PORT=1521))(CONNECT_DATA=(SERVICE_NAME=racpoc.domain1.com)(FAILOVER_MODE =(TYPE = SELECT)(METHOD = BASIC)(RETRIES = 180)(DELAY = 5))))" />
$ nslookup scan-cluster
Server:         128.191.2.13
Address:        128.191.2.13#53
Name:   scan-cluster.domain2.com
Address: 128.191.224.227
Name:   scan-cluster.domain2.com
Address: 128.191.224.29
Name:   scan-cluster.domain2.com
Address: 128.191.224.30

The Java Script to test Oracle Connection is :

import java.sql.*;
public class testconn {
public static void main(String[] s)throws Exception {
Class.forName("oracle.jdbc.OracleDriver");
String url="jdbc:oracle:thin:@(DESCRIPTION= (LOAD_BALANCE=on) (ADDRESS=(PROTOCOL=TCP)(HOST=scan-cluster)(PORT=1521)) (CONNECT_DATA=(SERVICE_NAME=racpoc.domain)))";
for (int i=0; i<20; i++) {
try {
long x= System.currentTimeMillis () ;
Connection conn = DriverManager.getConnection(url,"askm","askm");
long y= System.currentTimeMillis ();
System.out.println("Connection Succesful "+conn);
System.out.println("Connection time is "+(y-x)/1000+" ms");
Statement stmt =conn.createStatement();
ResultSet res= stmt.executeQuery(" select host_name from v$instance");
while(res.next()) {
System.out.println(res.getString(1));
}
stmt.close();
conn.close();
}
catch(Exception e) {
e.printStackTrace();}}}}

Hope it helps
SRI

In the present article i will show you how to install 10gR2 grid control and also how to install agents on different hosts linux and windows to monitor databases.

This demo is prepared assuming that you already have 2 linux servers and 1 windows server created in vmware.

The following topics are demonstrated ...

1. Installing 10gR2 grid control(OMS) on linux machine with new repository database and test the server URL.
2. Installing agents on linux server with existing database
3. Installing agents on linux when creating a new database with DBCA
4. Installing agents on windows server with existing database
5. Installing agents on windows when creating a new database with DBCA

Hope It Helps

SRI

In the present article i am going to show you how to move the spfile located on ASM diskgroup to the file system. This may not be the practical requirement in the RAC as we need common place for the spfile to store. If we move spfile to local file system in RAC, then it is very hard to keep the spfiles on all the nodes in sync. But it will be useful if you are trying to change any non-dynamic parameter in the spfile.

Thats fine, how do we manage spfile, but lets see  the process how do we move the spfile located in ASM to the file system.

Hope it helps

SRI

The present article describes how to troubleshoot  if you are not able delete an ASM disk from  the ASM storage. The troubleshooting technique may vary from person to person and the following article describes the technique  i used to drop an ASM disk. There may be so many other possible solutions to the issue, but the one presented here worked for me.

The present issue is that , i have to delete an ASM disk from the ASM storage. The disk is already marked as ASM disk and when i try to unmark it for ASM disk, it throws an error. So i cant delete the OS disk without deleting it from the ASM disks.

Present issue occured in 11gR2 RAC on linux and we are using multi path ASM disks for the storage.

So i verified the log file  /var/log/oracleasm and the content of the log file shows me the following error

I tried creating a diskgroup with this ASM disk and droped it and then tried to delete the ASM disk, but no use.

I verified with the following command if the disk is still marked as ASM disk or not. It is still marked as ASM disk.

Then i tried clearing the disk with the OS command dd.

Now i am able to successfully delete the disk from ASM disk list.

On all other nodes in the RAC , do the following to sync

Content from the log file /var/log/oracleasm now shows ...

Hope it helps

SRI