SAP Note 23139 - Deactivate mirroring of online redo logs

Symptom:

The software mirroring of the online redo logs should be deactivated.

Solution

WARNING: The loss of online redo logs is a disaster. In case of recovery each of them must be 100% intact. This is the reason for software mirroring. Mirroring can also be done via other means (RAID technology), but we do NOT recommend it. It is less safe, and the gain in performance is rather small.

If you still want to do it (your risk!) the Procedure is as follows (example: System "FUN" on WindowsNT):

1. Remove the mirrored online redo logs with

alter database drop logfile member 'F:\oracle\FUN\saplog2\log_g0_m2.dbf';
alter database drop logfile member 'F:\oracle\FUN\saplog2\log_g1_m2.dbf';
alter database drop logfile member 'F:\oracle\FUN\saplog2\log_g2_m2.dbf';
alter database drop logfile member 'F:\oracle\FUN\saplog2\log_g3_m2.dbf';

2. Delete the directory F:\oracle\FUN\saplog2 and its contents.

Remark: You can list the status of the online redologs using the SQL statement

• select * from v$log;
  

The mirror image of the active logfile can be dropped after forcing the switch to another logfile using the SQL statement

alter system switch logfile;