Advice

Can I have redo log groups with different size?

Cairon Davison

Can I have redo log groups with different size?

All members of the same multiplexed redo log group must be the same size. Members of different groups can have different sizes. However, there is no advantage in varying file size between groups.

How do I know the size of my redo log block?

Unlike the database block size, which can be between 2K and 32K, redo log files always default to a block size that is equal to the physical sector size of the disk. Historically, this has typically been 512 bytes (512B).

How do I change the redo log size in Oracle?

Here in this post, I will show you how to resize redo logs from 50MB to 1GB step by step.

  1. Check Current Redo Logs.
  2. Add 3 Groups with New Size (1GB)
  3. Switch Logfile to New Groups.
  4. Force a CheckPoint.
  5. Drop Group 1, 2, 3.
  6. Remove Redo Log Files.
  7. Add Group 1, 2, 3 with New Size (1GB)
  8. Switch Logfile Several Times.

How many maximum redo logfiles one can have in a database?

Post 10.2. 0 oracle specified that there is no limitations in the number of redo logfiles,where the controlfiles will extends its size if the more number of redo logfiles created irrespective to the MAXLOGFILES specified. , Oracle Database specialist since 1995.

How do you increase the size of a redo log in Oracle 12c?

select group#, status from v$log; You may have to run the alter command up to three times to get group 1 to be CURRENT. Repeat steps 1 to 7 for group 2, group 3, and group 4. Confirm the size change to each group is now 165 Mb.

How do I rename a redo log in Oracle 12c?

To rename redo log members, you must have the ALTER DATABASE system privilege….

  1. Shut down the database.
  2. Copy the redo log files to the new location.
  3. Startup the database, mount, but do not open it.
  4. Rename the redo log members.

When should I increase redo log size?

As a general rule of thumb, Oracle recommends that you size your online redo logs not to switch more then 5 times per hour during peak DML times.

How do I manually use redo logs?

To apply the archived redo logs in the archive gap

  1. Start up and mount the standby database (if it is not already mounted).
  2. Recover the database using the AUTOMATIC option:
  3. Cancel recovery after the Oracle database server has applied the available logs, by executing the following statement (or typing CTRL+C):

How do I restore a redo log in Oracle?

Step-By-Step Guide

  1. Run the following code to check to see what log is currently in use. set lines 180.
  2. Make a note of the current log file group.
  3. Drop and recreate logfile group 1.
  4. Repeat the process for logfile group 2 and 3.
  5. Switch log file group to free up log file group 4.
  6. Drop and recreate logfile group 4.

How do I drop a redo log in Oracle?

To drop specific inactive redo log members, use the ALTER DATABASE statement with the DROP LOGFILE MEMBER clause. The following statement drops the redo log /oracle/dbs/log3c. rdo : ALTER DATABASE DROP LOGFILE MEMBER ‘/oracle/dbs/log3c.

How do you increase a redo log?

How do I rename a redo log?

What is the recommended redo log switch frequency in Oracle?

Ideally redo log switch frequency should be 4-5 log switches per hour. If there is frequent log switches then check the size of redo logs and increase accordingly. V$LOG_HISTORY is used to check history of redo log generation in Oracle.

How to check the size of redo logs in Oracle?

If there is frequent log switches then check the size of redo logs and increase accordingly. V$LOG_HISTORY is used to check history of redo log generation in Oracle. V$LOGFILE is used to check the file name and location of redo logs. V$LOG and V$LOGFILE view can be combined to get the detailed information like redo log size, redo log members,

How many frequent log switches per hour should there be?

There should not be frequent log switches per hour. Ideally redo log switch frequency should be 4-5 log switches per hour. If there is frequent log switches then check the size of redo logs and increase accordingly. V$LOG_HISTORY is used to check history of redo log generation in Oracle.

What do the numbers next to the redo log file mean?

Figure 11-1 illustrates the circular writing of the redo log file. The numbers next to each line indicate the sequence in which LGWR writes to each redo log file. Filled redo log files are available to LGWR for reuse depending on whether archiving is enabled.