Redo Log Corruption

[Former Member]

Hi All,

Just a question, earlier during our recovery, we faced a corrupt redo log file. To avoid applying corrupted this redo log file into the target system (homogeneous copy using TSM backup/restore method) we want to know if there is a procedure for checking the corrupted redo logfile.

Oracle 9i

SAP R3 Enterprise Release 1 (4.7 Ext 1)

Anyhelp in this is very much appreciated.

Thanks and Regards,

Giridhara Tadikonda

[stefan_koehler]

Hi Giridhara,

I am not a corruption specialist.. but yes there is a method to avoid this:

http://download.oracle.com/docs/cd/B10501_01/server.920/a96521/onlineredo.htm#8172

Quote from the oracle documentation:

> If you enable block checking, Oracle computes a checksum for each redo log block written to the current log. Oracle writes the checksum in the header of the block. Oracle uses the checksum to detect corruption in a redo log block. Oracle tries to verify the redo log block when it writes the block to an archive log file and when the block is read from an archived log during recovery.

> If Oracle detects a corruption in a redo log block while trying to archive it, the system attempts to read the block from another member in the group. If the block is corrupted in all members the redo log group, then archiving cannot proceed.

If you are using RMAN - you can also query the view V$BACKUP_CORRUPTION:

http://download.oracle.com/docs/cd/B10501_01/server.920/a96536/ch314.htm#1110218

Regards

Stefan

[Former Member]

This is the solution as such. I was told by our DBA's that there will be an overhead of 2% or so for database. But not confirmed until we test that. If you have any update on how much overload, let me know...

Thanks and Regards,

Giridhara Tadikonda