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Data Guard redo configuration asynchronous mode, the Log Network Server (LNS) process will attemp to read redo directly from the log buffer. If the redo to be sent is not found in the log buffer, then the LNS process will go to the Online Redo Log (ORL) to retrieve it. Size the log buffer so that LNS is always able to find the redo that is needs to send within the log buffer. The log buffer hit ratio is tracked in the view x$logbuf_readhist . A low hit ratio indicates that the LNS is frequently reading from the ORL instead of the log buffer. If there are periods when redo transport is coming close, but is not quite keeping pace with your redo generation rate, consider increasing the log buffer size in Data Guard 11g to achieve a favorable hit ratio.

In 11gR2, Oracle has introduced a new registry to maintain the clusterware resources (css, crs,evm,gip and more) in a new registry called Oracle Local Registry (OLR) . Multiple processes on each node have simultaneous read and write access to the OLR particular to the node on which they reside, regardless of whether Oracle Clusterware is running or fully functional. By default, OLR is located at Grid_home/cdata/host_name.olr on each node.The OCR still exists, but maintains only the cluster resources. Until Oracle Database 11gR1, the RAC configurations consisted of just one registry when running Oracle Clusterware. Shortly called OCR, Oracle Cluster Registry, maintained the cluster level resource information, privileges etc. To be precise, the OCR maintained information about 2 sets of node level resources, namely, the Oracle Clusterware Components (CRS, CSS, evm) as well as Cluster resources (DB, Listener etc).

Step-By-Step - DBconsole RAC Uninstall WARNING: The uninstall process will Quiesce the database. Do not run on a live system 1. Ensure you have the following information before continuing. Database unique name Listener port number Password for SYS user Password for SYSMAN user 2. Log onto any node in the cluster. 3. Set-up your environment . oraenv ORACLE_SID = [SID] ? enter sid 4. Deconfigure dbconsole and drop the repository emca -deconfig dbcontrol db -repos drop -cluster

We encountered a shutdown issue with 11gR2 Clusterware on Redhad 5.4 We encountered a shutdown issue with 11gR2 Clusterware and Redhad 5.4. The services would start fine, but the shutdown script never appeared to run before the shutdown of the OCFS2 . This results in a not clean shutdown of the instance on the node. The Solution To solve this problem we have done to actions: During the start stanza of the script, put in a command: touch /var/lock/subsys/ohasd Change the K19ohasd to K18ohasd in the /etc/rc?.d

One of the challenges I faced recently was building a virtual cluster based on Oracle 11gRelease 2 on top of Oracle Enterprise Linux (OEL) running inside VMware server.. I’ll save the story about building the actual cluster for another posting. I will share a solution on how to get around the DNS requirements without making changes to the business corporate DNS server. With this you can solution you can test the SCAN functionality and maybe even the Grid Naming Service (GNS). Read on the post of Harold van Breederode  more

As a virtual machine environment user, I regularly create ‘base’ images of machines that I can reuse . So when I need a new machine, I simply create a copy of the virtual disk and add any additional software I need, this save me a lot of time instead creating new virtual environments. In VirtualBox, copying a virtual disk is a bit of a pain. If you copy the disk in Windows Explorer and try and use it in a new VM, VirtualBox will have a display an error shown below.

What are Oracle JDBC drivers ? [Using Service Name instead of SID] JDBC is an API that allows Java programs to access any tabular data source. In order to interact with an Oracle Database from a Java program using JDBC interface, Oracle provides its own Oracle JDBC drivers. Oracle provides drivers that enable users to make JDBC connections to Oracle databases. The two most common methods of connecting to Oracle databases via JDBC are the Oracle Thin JDBC driver and the Oracle OCI JDBC driver. The Oracle Thin driver requires no software other than the driver jar file. This driver connects to Oracle databases via TCP/IP. The Oracle OCI (Oracle Call Interface) driver requires Oracle client software to be installed on the user's machine in order to connect to the database. This driver uses native methods and is platform specific. The Java classes to connect to Oracle are contained in the Oracle JDBC driver jar file. For recent releases, these are numbered based on the Java v...