We all know that redo log has three kinds of a group like active, inactive, current. They all have different use and as well as different meaning.Let’s simulate a loss of all redo log members of an inactive group.

If you have completely lost one redo log group your database won’t be able to open.
Next thing is to know the STATUS of the lost redo log group (we know it because we are simulating the loss, but…) and, just because this information is on V$LOG view, try to get also the ARCHIVED column.
Now if the redo log group lost was INACTIVE and archived (YES value) we can simply recreate all members with the “alter database clear logfile” command;
if it was INACTIVE and not archived (NO value) we’ll execute the “alter database clear unarchived logfile” command.

Let’s look at the example. Here is my redo log group state

Delete all members of redo log group 1 and kill your instance.

Try to open your database

look at your alert log

Start your database in MOUNT mode

Query the V$LOG view

The redo log group 1 is INACTIVE and ARCHIVED so simply issue the following command:

Open your database

If you are in the situation to have lost an INACTIVE and NOT already ARCHIVED redo log group then your command should be the following:

Next step is to perform a complete backup

Thank you for giving your valuable time to read the above information.

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