This image shows two disks, DISK A and DISK B, containing online redo log files. Each disk contains identical online redo log files. LGWR writes concurrently to the online redo log files. Each identical set of redo log files is called a group. This image shows two groups.Group 1 consists of the following members:
redo01a.log on Disk A
redo01b.log on Disk B
Group 2 consists of the following members:
redo02a.log on Disk A
redo02b.log on Disk B
End of image description.