Contents
What is the importance of redo logs?
The most crucial structure for recovery operations is the redo log, which consists of two or more preallocated files that store all changes made to the database as they occur. Every instance of an Oracle Database has an associated redo log to protect the database in case of an instance failure.
What does redo log file contains?
Which statement is true about redo log files during instance recovery?
Which statement is true about redo log files during instance recovery? A. All current, online, and archived redo logs are required to complete instance recovery.
What are the archived redo logs used for?
The archived redo log contains a copy of every group created since you enabled archiving. When the database is running in ARCHIVELOG mode, the log writer process (LGWR) cannot reuse and hence overwrite a redo log group until it has been archived.
Can I delete redo log files?
You can drop a redo log member only if it is not part of an active or current group. If you want to drop a member of an active group, first force a log switch to occur. Make sure the group to which a redo log member belongs is archived (if archiving is enabled) before dropping the member.
How do I find the redo log file?
The redo log files are initially specified within the CREATE DATABASE command. CREATE DATABASE . . . LOGFILE ‘/t02/oradata/MYDB/redo1.
How do I recover a redo log file?
Recovering After the Loss of All Members of an Online Redo Log Group
- Locate the filename of the lost redo log in V$LOGFILE and then look for the group number corresponding to it.
- Determine which groups are active.
- If the affected group is inactive, follow the procedure in Losing an Inactive Online Redo Log Group.
When do I need to create redo log files?
When databases are created at least two redo log files are created. A paranoid DBA might create two groups of log files where group members are mirror images of each other. Redo log files are used to record data changes to the database. The redo log files are initially specified within the CREATE DATABASE command. CREATE DATABASE . . .
Is it possible to resize redo logs to 1GB?
As for the databases that you took over from other DBA, 50MB of redo logs could be very annoying because it makes log switching very frequently and causes a lot of trivial files. Here in this post, I will show you how to resize redo logs from 50MB to 1GB step by step.
How is Oracle database writes to the redo log?
How Oracle Database Writes to the Redo Log The redo log of a database consists of two or more redo log files. The database requires a minimum of two files to guarantee that one is always available for writing while the other is being archived (if the database is in ARCHIVELOG mode). See “Managing Archived Redo Logs” for more information.
Why is my alter database redo log file corrupt?
The reason is: If the status of your redo log file is CURRENT then there is no archive log file created of that particular redo log file. Hence we cannot run ALTER DATABASE CLEAR LOGFILE. 1 INACTIVE C:\\APP\\PC\\ORADATA\\ADMIN\\ REDO04.