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Oracle Architecture - Explained In Detailed - Administration I

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Figures shown in these notes are from Oracle® Database Concepts 11g Release 2

Objectives
These notes introduce the Oracle server architecture.The architecture includes physical components, memory components, processes, and logical structures.


Primary Architecture Components


The figure shown above details the Oracle architecture.
Oracle server:An Oracle server includes an Oracle Instance and an Oracle database. ·An Oracle database includes several different types of files:datafiles, control files, redo log files and archive redo log files.The Oracle server also accesses parameter files and password files. ·This set of files has several purposes. oOne is to enable system users to process SQL statements. oAnother is to improve system performance. oStill another is to ensure the database can be recovered if there is a software/hardware failure. ·The database server must manage large amounts of data in a multi-user environment. ·The server must manage concurrent access to the same data. ·The server mu…
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Step by Step - How to resolve redo log file corruption using ALTER DATABASE CLEAR UNARCHIVED LOGFILE command

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Connect to sys using sqlplus in admin command prompt
Check whether your database is in archive log mode or not. Run command ARCHIVE LOG LIST. It will show you the following details:
It is always preferable to have your database in archive log mode. The reason being if your database is in archive log mode you can recover from all committed changes in the event of an OS or disk failure.
This query will display the path of redo log files, their group and their status. It is always recommended to have a minimum of two members in one group.

As you can see I have only 1 member in group 6 whose current status is INACTIVE. I intentionally have 1 member to generate a scenario for the sake of this practical.

Now go to the specified path where the redo log member of group 6 is located and open it in a notepad. It will show some symbolic data. Delete couple of lines and save it the original location which is the one we got as a result of query.

Why did we do the above step i.e. why did…
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