Tuesday, January 31, 2017

Transparent Data Encryption in 11g

In this article I would discuss how to implement Transparent Data Encryption (TDE) in 11g. TDE is used to encrypt data at table/column level or tablespace level. This ensures that encrypted data is accessible only by using encryption key that is stored in either Wallet or Hardware Security Module.
For RAC setups, encryption key needs to be stored/copies on all the RAC nodes. In dataguard setup, encryption key should also be copied on dataguard sites.

Monday, January 23, 2017

ORA-28365: wallet is not open

This error means that you are trying to perform some operation in the database which requires encryption wallet to be open, but wallet is not open. In 11g, use following command to open the wallet. Provide password after “identified by” clause. In the following scenario, password is “welcome”.
alter system set encryption wallet open identified by "welcome1";

Saturday, December 31, 2016

OEM Cloud Control Job Suspended - Target is not ready

In my OEM 12c, my RMAN backup job for one target database started failing, and next execution status was marked as "Suspended".

Wednesday, October 26, 2016

DUPLICATE Database using Backup of a Database

If you want to create a duplicate database from a live/active database, you can follow this article. But if you want to DUPLICATE a database using backup of another database, you can use following steps. I am creating new database with a different name using DUPLICATE command, or you may want to retain same name for the database while duplicating.

Friday, October 14, 2016

Configuring OEM Express Control

Starting 12c, OEM Database Control has been replaced by OEM Database Express. OEM Express configuration is very simple as compared to previous OEM Database Control. Following is the method to configure OEM Express. OEM Express Database is configured separately for container database and each pluggable database. Method is same; you just need to set current container to pluggable database for which you want to configure the OEM, and execute the steps as explained bellow.

Tuesday, October 4, 2016

Calculating ASM diskgroup Usable Size

Sometimes sizing information of an ASM diskgroup returned by “lsdg” command from “asmcmd” prompt (similar information is also available under v$asm_diskgroup view) leaves DBAs perplexed. Sizing information and usable space for diskgroups with EXTERNAL REDUNDANCY is quite easy to understand, but when it comes to NORMAL or HIGH redundancy diskgroups, it is not very straightforward. Here I would explain ASM diskgroup space calculation in detail to make it easier to understand. Before I explain how to calculate usable space in an ASM diskgroup, some useful information to note is as follows

Tuesday, September 20, 2016

Linux Error: No Space Left on Device

On Linux machine, there could be several reasons for this error message appearing in some log file, or on the command line output while executing some command. Most of the time we immediately start checking if our file system has still sufficient space left, but file system space is not the problem most of the time. Following are a few of them I will be discussing.

Monday, September 12, 2016

Enable Asynchronous IO for file System using FILESYSTEMIO_OPTIONS

We noticed that on one of our standby database, the log apply was quite slow. I stopped managed recovery process which showed ORA-16037 in the alert log file along with trace file name.
ALTER DATABASE RECOVER managed standby database cancel
Fri Nov 20 16:13:12 2015
RFS[2]: Selected log 12 for thread 1 sequence 504809 dbid -1228626264 branch 748801133
Fri Nov 20 16:13:13 2015

Thursday, August 11, 2016

Backing up OEM Cloud Conrol 12c, 13c

Just like any other application or database deployment, we should also devise a backup and recovery policy for the OEM deployments. Here I would discuss how we devise a backup policy to back up our OEM 13c (and also previous versions) deployment. Following are the major components that should be considered for the backup. Official documentation explains this in more detail

Sunday, July 17, 2016

Starting and Stopping OEM Cloud Control 13c

After you have installed OEM Cloud Control 13c, you should know how to start and stop the OEM components. Here I will explain the sequence of starting and stopping OEM 13c components and same steps could be used for starting and stopping OEM cloud control 12c. For this example, my $ORACLE_HOME (OEM repository database home) is /u01/app/oracle/product/12.1.0/db, $OMS_HOME is /u01/software/em/middleware, and $AGENT_HOME is

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