ORACLE RAC Troubleshooting Best Practices

When we are working with Oracle RAC setup before start the database we want to know weather the Cluster environment service are on line.The below commands are generally used to check the status of Cluster environment.

Checking CRS Status:

The below two commands are generally used to check the status of CRS. The first command lists the status of CRS on the local node where as the other command shows the CRS status across all the nodes in Cluster.

crsctl check crs <<-- for the local node
crsctl check cluster <<-- for remote nodes in the cluster

[grid@rac1 ~]$ crsctl check crs
CRS-4638: Oracle High Availability Services is online
CRS-4537: Cluster Ready Services is online
CRS-4529: Cluster Synchronization Services is online
CRS-4533: Event Manager is online
For the below command to run, CSS needs to be running on the local node. The "ONLINE" status for remote node says that CSS is running on that node. When CSS is down on the remote node, the status of "OFFLINE" is displayed for that node.

[grid@rac1 ~]$ crsctl check cluster
CRS-4537: Cluster Ready Services is online
CRS-4529: Cluster Synchronization Services is online
CRS-4533: Event Manager is online

No Of Nodes configured in Cluster:
The below command can be used to find out the number of nodes registered into the cluster. It also displays the node's Public name, Private name and Virtual name along with their numbers.
[grid@rac1 ~]$ olsnodes -n -i -s
rac1    1       rac1-vip        Active
rac2    2       rac2-vip        Active

[grid@rac1 ~]$ crsctl query crs activeversion
Oracle Clusterware active version on the cluster is [11.2.0.1.0]

[oracle@rac1 ~]$ cluvfy comp crs -n all -verbose

Verifying CRS integrity

Checking CRS integrity...
The Oracle clusterware is healthy on node "rac2"
The Oracle clusterware is healthy on node "rac1"

CRS integrity check passed

Verification of CRS integrity was successful.

Backups & Restore of MySQL Databases Using mysqldump

If you work with MySQL at any level you may need to backup your databases & restore.MySQL is most popular open source RDBMS widely use.MySQL that has always disappointed me  because of there are so many free tools for backing up databases confused when selecting the exact tool.Backups are extremely easy in MySQL to create with mysqldump."mysqldump" is the only backup tool that most MySQL users know and use, and it’s available whatever MySQL.

Database Backup

Backup a single database
 you can also use the shortcuts -u and -p to specify username and password
mysqldump --user=... --password=...   your_database_name >  your_database_name.sql

Backup multiple databases
mysqldump --user=... --password=... --databases db1 db2 > backup.sql

All the databases
mysqldump --user=... --password=... --all-databases > backup.sql

Restoring DB Backup

Created the destination database & then created the users & give appropriate privileges.Restoring is usually done this way:

mysql –u root –p[password] restoredbname < dbname_backup.sql

Watching Content of Embedded H2 Database Through Browser in WSO2 Products

H2 is a RDBMS written in Java.This database can be used in embedded mode,only thing is add the h2*.jar to the class path & do not have any other dependencies.All the WSO2 products are default shipped with H2 database.Graphical interfaces to run SQL commands and display their results. there are H2 Database Query Tool also available.


1. Download a  WSO2 product and extract

2. Open the file "carbon.xml" in the location repository/conf

3. Enable the followe H2DatabaseConfiguration only

<H2DatabaseConfiguration>
        <property name="web" />
        <property name="webPort">8082</property>
        <property name="webAllowOthers" />
        <!--property name="webSSL" />
        <property name="tcp" />
        <property name="tcpPort">9092</property>
        <property name="tcpAllowOthers" />
        <property name="tcpSSL" />
        <property name="pg" />
        <property name="pgPort">5435</property>
        <property name="pgAllowOthers" />
        <property name="trace" />
        <property name="baseDir">${carbon.home}</property-->
    </H2DatabaseConfiguration>
</Server>

In here we do not need to start PG server therefor only enabling
        <property name="web" />
        <property name="webPort">8082</property>
        <property name="webAllowOthers" />
is enough

4. Save the file and close

5. Start the server


So now that If wanted to watch the content of this db browser page should open with the URL http://localhost:8082 to in browser


Login

Select [Generic H2] and JDBC URL : jdbc:h2:<file path to CARBON_HOME>/repository/database/WSO2CARBON_DB
username : wso2carbon
password  : wso2carbon

 You are now logged in & ow h2 database use WSO2 client that can run SQL commands and display their results