Dumping Redo Logs

To identify the current redo log use

    SELECT member FROM v$logfile

    WHERE group# = 

    (

        SELECT group# FROM v$log

        WHERE status = 'CURRENT'

    );

To dump a redo log file use

    ALTER SYSTEM DUMP LOGFILE 'FileName';

e.g.

    ALTER SYSTEM DUMP LOGFILE 'R:\Oracle\Oradata\JD92001\Redo01.log';

The syntax of this statement is as follows

    ALTER SYSTEM DUMP LOGFILE 'FileName'

        SCN MIN MinimumSCN

        SCN MAX MaximumSCN

        TIME MIN MinimumTime

        TIME MAX MaximumTime

        LAYER Layer

        OPCODE Opcode

        DBA MIN FileNumber . BlockNumber

        DBA MAX FileNumber . BlockNumber

        RBA MIN LogFileSequenceNumber . BlockNumber

        RBA MAX LogFileSequenceNumber . BlockNumber;

The minimum and maximum SCN is a decimal number
The minimum and maximum time is a decimal number representing the number of seconds since midnight 01Jan1988. These are calculated using the following formula

    time = (((((yyyy - 1988)) * 12 + mm - 1) * 31 + dd - 1) * 24 + hh) * 

           60 + mi) * 60 + ss;

where

yyyy Year &nbsp mm month 01-12 dd day 01-31 hh hour 00-23 mi minute 00-59 ss second 00-59

This is the same formula that is used to represent time within the redo log
The layer and opcode are those used to indicate specific operations within the redo log e.g. LAYER 5 OPCODE 4 is an undo segment header commit operation
Note that there must be spaces around the periods in the DBA and RBA.
See Metalink Note 1031381.6 for further examples