Restoring a Mirrored Log Volume 
If your 
log volumes are
mirrored, it is possible that one of the volume mirrors may fail. If there are
problems accessing the log area or the mirror log area, the affected log
volume is flagged as BAD, and the database instance is transferred to the
OFFLINE operational state.
You can use the Database Manager GUI to restore a damaged mirror log volume. When you do so, the complete content of the relevant log volume is copied from the other log area to the faulty log volume. This ensures that, if disk errors destroy the content of a log volume, the database instance does not need to be restored, since the content of the log volume is mirrored.
Prerequisites
The database instance is in the ADMIN operational state.
Procedure
1.
Choose Instance ® Recovery ® Volumes.
Select the BAD volumes that you want to recover.
2. Choose Actions ® Reintegrate to start copying the mirror volume.
See also: