How do you resolve redo log corruption?
How do you resolve redo log corruption?
If the corrupt redo log file has not been archived, use the UNARCHIVED keyword in the statement. ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 3; This statement clears the corrupted redo logs and avoids archiving them. The cleared redo logs are available for use even though they were not archived.
What does redo log file contain?
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.
How do I reduce the redo log in Oracle?
In order to reduce the redo log generation, DBAs can increase the main memory cache size, one should also increase the commit frequency to reduce the disk i/o. However, for the faster i/o, DBAs can add more disk chains, for an economic solution, if cost is not the factor then it is suggested to use SSD disks.
How do I find the current redo log file?
The V$LOGFILE view can be used to find the datafiles for the redo logs. SVRMGR> select * from V$LOGFILE; GROUP# STATUS MEMBER —— —— —————————— 1 /t01/oradata/MYDB/redo.
Can we delete redo log files?
It is permissible to drop redo log files so that a multiplexed redo log becomes temporarily asymmetric. For example, if you use duplexed groups of redo log files, you can drop one member of one group, even though all other groups have two members each.
How do I restore a redo log?
Recovering After the Loss of All Members of an Online Redo Log Group
- Locate the filename of the lost redo log in V$LOGFILE and then look for the group number corresponding to it.
- Determine which groups are active.
- If the affected group is inactive, follow the procedure in Losing an Inactive Online Redo Log Group.
Why do we need redo log?
What Is the Redo Log? The most crucial structure for recovery operations is the redo log, which consists of two or more preallocated files that store all changes made to the database as they occur. Every instance of an Oracle Database has an associated redo log to protect the database in case of an instance failure.
What is redo log files in vmware?
Redo logs are auxiliary files used to keep changes that take place when VMs run in the virtual lab. By default, redo logs are stored on the vPower NFS server. However, you can store redo logs on any datastore in the virtual environment.
What is redo log size?
The minimum size permitted for a redo log file is 4 MB. See Also: Your operating system–specific Oracle documentation. The default size of redo log files is operating system dependent.
How do you make a redo log inactive?
Ensure your redo log group is INACTIVE by querying V$LOG. If ACTIVE, switch the log (ALTER SYSTEM SWITCH LOGFILE) and wait until the status is INACTIVE. Next, drop the online redo log (with the ALTER DATABASE DROP LOGFILE GROUP x) command.
How do you rename redo log file online or offline?
To rename redo log members, you must have the ALTER DATABASE system privilege….
- Shut down the database.
- Copy the redo log files to the new location.
- Startup the database, mount, but do not open it.
- Rename the redo log members.
What is size of redo log file?
What is the current status of redo log file 2622?
LOG 2622 You can see that status of redo log files in group 2 is CURRENT (in 1st query) and a big NO in front of group 2 (in 2nd query. Also displays the status, which is CURRENT). And also database won’t allow you to drop the redo log file whose status is CURRENT.
How many redo log files should I have in a group?
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.
What happens when the redo log file is skipped?
When a corruption in the redo log file is skipped, the OPERATION column contains the value CORRUPTED_BLOCKS, and the STATUS column contains the value 1343. If the LogMiner dictionary in use is a flat file or in the redo log files, LogMiner updates its internal dictionary if a DDL event occurs.
What is active and inactive redo log in Oracle?
Active (Current) and Inactive Redo Log Files Oracle Database uses only one redo log files at a time to store redo records written from the redo log buffer. The redo log file that LGWR is actively writing to is called the current redo log file. Redo log files that are required for instance recovery are called active redo log files.
