Problems with big SGAs (>200G) on Linux

I recently had an issue where a database with 240GB SGA (1 huge shared memory segment) configured with hugepages on a system with 512G RAM was suddenly becoming instable and new logons were denied with these error message:

ORA-01034: ORACLE not available
ORA-27123: unable to attach to shared memory segment
Linux-x86_64 Error: 22: Invalid argument
Additional information: 2667
Additional information: 1736718
Additional information: 215016800256

This was strange because ipcs -a showed all shared memory segments (more...)

#DB12c feature – Secure External Procedures with DBMS_CREDENTIAL

Oracle Database 12c enables enhanced security for extproc by authenticating it against a user-supplied credential. This new feature allows the creation of a user credential and links it with a PL/SQL library object. Whenever an application calls an external procedure, the extproc process authenticates the connection before loading the shared library. The DBMS_CREDENTIAL package is … Continue reading

AWR Warehouse – security issue

During implementation of AWR Warehouse, I discovered that AWR warehouse is using temporary staging schemas in the AWR warehouse repository database. These schemas life approximately for the duration of a datapump import job and are then dropped again. Due to the fact that the used password is not compliant with customers password verification function, the jobs failed.


Adding Log Groups on Oracle DataGuard Database

When adding Redo logs to a database which has a DataGuard associated with it, the log files have to manually be added to the destination. Below are the steps on how to add them to both the source and the DataGuard databases. Adding Log Groups on Oracle DataGuard Database On the source first determine the […]

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Want to SPEED Up Your Database Tasks? DBMS_PARALLEL_EXECUTE to the rescue!

Use DBMS_PARALLEL_EXECUTE to divide one huge task into multiple small tasks that can be executed at the same time. See how many ways are there to divide.

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Oracle 12c enqueue waits

Just as with the new Oracle 12c lock types it’s time to take a quick look at the new enqueue waits in 12c. Oracle had a total of 304 enqueue waits. 12c has a total of 418. A lot of work seems also to have happened (more...)

Why use OVM for Oracle Databases

Some time ago I made a benchmark exercise to compare the performance of an Oracle Database running in a bare metal environment versus a virtualized environment to clear some of the main questions our team and clients in Revera have,

Rotate 11G XE database and listener logs

Rotate 11G XE database and listener logs on Linux using logrotate

Oracle Restart – a 11g New Feature

Oracle Restart is a new feature introduced to enhance the availability of Oracle database. I wasn't aware of this till recently. It basically allows various components of Oracle to restart automatically in a stand-alone (non-clustered) installation. This functionality is similar to what Clusterware does in a RAC setup. On Windows and Linux, we were able to achieve all this via creating a service or writing a script. But now it’s not required. So in a way, it also makes the age old practice of writing scripts to restart redundant.

Oracle instances and its dependent components restart automatically after any hardware (more...)

Oracle Database on Amazon RDS

Recently, Amazon and Oracle announced that they are going to make "Oracle 11g Database" available on Amazon AWS as a service. It's being brought into AWS's RDS feature which currently offers "MySQL database as a service".

Amazon RDS is a web service that allows you to set up, operate, and scale a relational database in the cloud. You can provision a relational database (currently only MySQL) on RDS in just a few minutes. Amazon RDS will also manage database administration tasks including continuous backups, software patching etc.
When launched (sometime in Q2 of 2011), you will have the option to (more...)