However, there are situations where you might want to create additional groups or members. If i drop group 2 and then add it again with these commands. Orneklerle oracle 11g r2 ve genel kavramlar oracle 11g r2 general concepts with examples was published as a book. Next, here are some examples of how to drop a group or member. Renamingdropping and recreating online redo logs and standby.
Method to drop and recreate online redolog files with 2 members to each group. Usually we do resize when redolog switches happen too frequently. Dec 12, 2015 tuning online redo logs in a rac environment. Jan 30, 2017 today we discuss about archive mode and no archive mode before that we have to remain what is redo log file. How to resize the online redo logfiles oracle rac dba. Using group numbers can make administering redo log groups easier. Find redo log members redo log file size redo log status. Oracle database cloud administrator certified professional. Oracle dataguard how to resize redo log and standby redo. Disabling an old rac instance thread the great grandson of. Oracle 11g oracle 12c rac oracle standby oracle goldengate mongodb postgresdb linux administration shell scripting sqlscripts wednesday, february 19, 2014 how to adddroprename standby redolog file how to droprename standby redolog file in oracle 11g. Multiplexing is a way to have a backup of redo log in oracle. Renamingdropping and recreating online redo logs and.
A group contains a redo log and all of its multiplexed copies. Aug 15, 2007 next, drop the online redo log with the alter database drop logfile group x command. Asm, how to resize redo on rac in this post, i try to explain how we can resize redolog files on rac instance while we have asm. How to resize online redo log files in rac database with asm option. Apr 19, 2010 multiplexing uses groups of redo log files. Jeffrey hunter is an oracle certified professional, java development certified professional. Premature redo log switching in oracle rac stack overflow.
The recommendation is to have log switches occur a few times an hour. I had a situation where i wanted to read the blocks of online redo log files. Or is just one additional group in one of the threads enough. Execute dbca from command line, it will open the welcome screen for dbca. The recommended log switch frequency is at least once an hour. How to add or increase the size of redo log files in rac environment. Mar 05, 20 how to resize redo log and standby redo log in oracle dataguard environment.
Managing the redolog in oracle11g ampersand academy. Actually we cant resize the redo logfiles we have to drop the redo logfile and then recreate the redo logfile again with the new size whatever we want. Recovering after the loss of online redo log files. This command will drop the redo log group, which is identified by number 6. In an oracle rac database, each instance must have at least two groups of redo log files. Rac tuning for redo logs oracle consulting, oracle. Mar 02, 2008 resizing the online redologs on a rac environment is a simple task, that require a little more attention than that of a single instance. Migrate an oracle rac database to new servers with zero downtime.
Oracle cloud infrastructure classic 2018 certified architect associate. The following statement drops redo log group number 3. Redo group 3 is active on instance 2 and instance acts as recovery instance once instance 2 is down, therefore redo group 1 is active on instance 2. Maa best practices dictates that to avoid such scenarios, we should be multiplexing the online redo log files.
Rac redo log thread maintenance burleson oracle consulting. If you have two diskgroup, you want to multiplex redo in different diskgroup, you just add redo log desitnation diskgroup. Firstly oracle will never allow you to drop the current online redolog file. For example, adding groups to a redo log can correct redo log group availability problems.
After all groups in database are filled it returns back to first redo log group. Rac redo log thread maintenance burleson consulting. For dropping an online redo log group, use the alter database statement with the drop logfile clause. Each group should have at least 2 members and each member should be located on a different physical disk. Renamingdropping and recreating online redo logs and standby logfiles. Archiving of redo log files is necessary for hot online backups, and is mandatory for pointintime recovery. Oracle grid book rac clusters dba book rampant books. Each database consists of two or more redo log files. Oracle database cloud service operations certified associate. Mar 22, 2007 redo buffers 6307840 bytes database mounted. After recreating an online redo log group, continue to recreate or resize all online redo log groups until all of them are rebuilt.
How to droprename standby redolog file in oracle 11g while performing the dataguard broker, we need to drop the standby database while switchover the standby. What are the possible causes of premature redo log switching in oracle other than reaching the specified file size and executing alter system switch logfile we have a situation where some but not all of our nodes are prematurely switching redo log files before filling up. Sep 01, 2016 add drop redo log groups in oracle rac. Disabling an old rac instance thread the great grandson.
Your course of action will depend on other factors you can read about in the. If a media failure damages all members of an online redo log group, then different scenarios can occur depending on the type of online redo log group affected by the failure and the archiving mode of the database. This article explains the steps for multiplexing redologs in oracle rac. He has handson experience with realworld production environments, and he has risen in the ranks from a developer to a managing dba.
The following article describes how to create an oracle rac 11gr2 physical standby database with active dataguard realtime apply enabled on linux. Find answers to delete redo log from the expert community at experts exchange. However, the group number must be between 1 and maxlogfiles. Oracle cloud infrastructure 2018 certified architect associate. Ive lost a member of the current redo log group so i cannot drop it. The information in this guide is not validated by oracle, is not supported by oracle, and should only be used at your own risk. Jan 10, 2015 how to multiplex redo log files in oracle 11g. Oct 09, 2014 how to resize online redo log files in rac database with asm option database setup has 2 nodes 11. Rac tuning for redo logs burleson oracle consulting. Tutorial on managing redo logfiles in oracle with step by step examples. Now the current redo log file will turns into active redo log file which means that file information are written into archive log through arcn once that written process is over an archive log then it turns into inactive redo log file creating group and member in redo log.
With an oracle rac standby db where the primary has 2 threads of 4 groups of online redo logs, should the standby db have 2 threads of 5 groups each. However there are simple command for reading the logfile. It is not possible to resize the redo log or standby redo log srl dynamically. I needed to resize the redo log as it takes about 4 days to do a log switch. For example, a file might be stored in an inappropriate location. Loss of a single current online redo log file will require us to restore the entire database and do an incomplete recovery.
Logwriter writes to redo log files in a circular fashion. Build your own oracle rac 11g cluster on oracle enterprise. Thatswhy it is recommended to multiplex the redo groups. Posted in oracle, ractagged disable thread, ora01567, rac, redo log groups6 comments. How to resize online redo log files in rac database with asm. Hi tom, on reading oracle document, there information about adding new log group is. For dropping an online redo log group, use the alter database statement with.
Recovering after the loss of all members of an online redo log group. How to add or increase the size of redo log files in rac. In particular the section titled recovering after losing of all members of an online redo log group. The files are written in oracle proprietary format and cannot be read directly. The source and target databases are 2node oracle rac 11gr2. Change ip address for oracle rac public and vip interfaces. After the completion of the refresh, saw 10 redo log groups. Covering all areas of oracle grid computing, this book is indispensable for any oracle dba who is charged with configuring and implementing oracle grid with server blades. So far as i know there is no fix for corrupted online redo log. To drop the old redo log files need to switch the log file on all the instance until all current online redologs are located on the newly added groups. Drop a redo log group with the sql statement alter database with the drop logfile clause. How to resize the redo logfile online redo logfile in. If you have a 100 log switches an hour with 50mb redo logs, you need e. Resize redolog file in oracle oracle blog by anar godjaev.
How to resize the redo logfile online redo logfile in oracle 11g. Dumping redo log file information oracle database 10g. Redo log files are written by redo log writter process. Rac and grid infrastructure administration exam 1z0068 and become oracle certified expert. How to resize the redo logfile online redo logfile in oracle. Oct 30, 20 this command will drop the redo log group, which is identified by number 6. Jan 02, 2008 redo log files are written by redo log writter process. How do i recreate a deleted logfile on an oracle database. Drop and recreate online redolog files oracle dba tips and. Oracle grid and rac is the firstofitskind reference for oracle grid computing. How can delete the redo log file alter database add std logfile group 4 u01apporacleoradata orclredo0 4.
Add or drop inactive online redo log files searchoracle techtarget. Plan the redo log of a database and create all required groups and members of redo log files during database creation. When a redo log group is dropped from the database, and you are not using the oraclemanaged files feature, the operating system files are not deleted from disk. This is not a strict rule, but generally happens most of the time.
It is not possible to resize the redo log or standby redo log srl. Because of that, there has to be at least 2 groups in an instance. The redo logfile contains the history of changes data in database group. Most database administrators know that it is good practice to have at least three orl groups for the database. How to resize the online redologs on a rac environment.
When you use dbca to create the database, dbca allocates redo log files to instances, as required, automatically. Oct 20, 2017 how to resize the redo logfile online redo logfile in oracle 11g. The online redo log orl for oracle rac is slightly different than a singleinstance database. Redo is the most crucial part when we talk about recovery and contains the current transaction details, hence if the data is redo is lost point time recovery is impossible depending on the scenario. Recovering from the loss of redo log files in the following post well go through every possible scenario where we loose redo, one by one. Dec 21, 2009 redo group 3 is active on instance 2 and instance acts as recovery instance once instance 2 is down, therefore redo group 1 is active on instance 2. Nov 29, 2007 especially to benefit from migrations most to remove the cbo parameters and let them to take their version specific default values and then monitor and tune is a better strategy. Oracle recommends an extra group for standbys but im not sure if that means per thread or not. With the group removed, add the group anew in the new location alter database add logfile command. Let us we discuss how to resize the redo logfile online redo logfile in oracle 11g. Multiplexing means to keep multiple copies of redo log in different diskgroup. Maintaining standby database as rac with active dataguard and a realtime apply feature allows using it for reading, backup, and testing by converting it over to a snapshot standby database and back after the completion. How to manage oracle redo logfiles oracle dba online.
I have two groups of redo logs that i want to resize. As part of the tests im using the drop database command, that made a fast and efficient cleanup of all datafiles, redologs and control files in one command. You can drop member from a log group only if the group is having more than one. Continue the above process until all logfile groups are moved to their new disk volumes.
The redo logfile contains the history of changes data in database jul 29, 2009 method to drop and recreate online redolog files with 2 members to each group. How to resize redo on rac instance with asm option helioss. To drop a redo log group, you must have the alter database system. Sql alter database drop std logfile group 4 u01apporacleoradata orclredo0 4. How to find the character set of the oracle database. Resizing the online redologs on a rac environment is a simple task, that require a little more attention than that of a single instance. Apr 29, 20 renamingdropping and recreating online redo logs and standby logfiles posted by dbakalyan on april 29, 20 we are in process of testing dataguard with physical standby. How to resize redo on rac instance with asm option.
Im testing cloning using rman, working with small databases, im performing several clones with different approaches, trying to find an optimal way to perform automatized cloning on demand. I have 3 redo log group, each group have only one member, is it safe to add a members to each group anytime. Oct 23, 2012 how to add or increase the size of redo log files in rac environment. First, i have to drop group 2 because group ones status is current. Can we add or drop inactive online redo log files at the open stage. Redo log files record changes made to the database and are used by oracle for system crash recovery. When a redo log group is dropped from the database, and you are not using the oracle managed files feature, the operating system files are not deleted from disk. Basically, we need to add new redolog groups in required diskgroup and drop the old ones. It is similar to that of multiplexing in standalone, only change is rac will have threads for node. How to resize online redo log files in rac database with. Recovering from the loss of redo log files oracle database. How to resize redo log and standby redo log in oracle dataguard environment. It is required that there are at least two groups and in the case of multiple members per group that all members be the same size.
It is recommend but not required that each group has the same number of. There are exception to this rule, suppose, your redo size is high and two log files were filled up quickly. Disconnected from oracle database 10g enterprise edition release 10. Add or drop inactive online redo log files searchoracle. Oracle 11g oce,oracle 12c and oracle 11g opn certified specialist, ocp certified in oracle 9i,10g, 11g and 12c. Build your own oracle rac 11g cluster on oracle enterprise linux and iscsi, page 3. Even the db is in archivelog mode you can do nothing if the redo log is corrupted. Firstly oracle will never allow you to drop the current. Rman recovery from loss of all online redo log files.