I have one doubt regarding RAC recovery on StandBy Site (or in general recovery mechanism of RAC), i am not able to figure how the consolidation of the redo log files from 'N' instances is done and applied at target standby site.

Theortical Case

Lets assume there are 2 instances in a RAC environment, 2 session running on different instances.

T1 Session1 Makes an update (and commit) on Tab1.Col1 to vaule x on instance 1. Lets assume SCN1 at this time.
T2 Session2 Makes an update (and commit) on Tab1.Col1, Tab1.Col2 to vaule y and z resp on instance 2. Lets assume SCN2 at this time.
T3 Session1 Makes an update (and commit) on Tab1.Col1 to vaule a on instance 1. Lets assume SCN3 at this time.
T4 Switch on Instance 1, thread 1 redo 1 would be shipped to standby site
T5 Switch on Instance 2, thread 2 redo 1 would be shipped to standby site

Now at standby site the archive/stand by redo (in case of online apply) would be applied as and when archive logs are shipped, even if it automatically selects which log to apply first and second, how will it handle the SCNs distributted across the logs?

Rgds
Abhay.