Checking block corruption, why in alert it is saying Error in trace file

Question

Hi,
I am using Oracle 10g 10.2.0.1 with linux 32 bit
I wanted to check block corruption using RMAN by following statement
backup validate check logical database;
when i executed the statement, following was the output
Starting backup at 09-MAY-08
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=91 devtype=DISK
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
input datafile fno=00004 name=/u01/app/oracle/oradata/test/users01.dbf
input datafile fno=00008 name=/u01/app/oracle/oradata/test/workflowuser
input datafile fno=00001 name=/u01/app/oracle/oradata/test/system01.dbf
input datafile fno=00003 name=/u01/app/oracle/oradata/test/sysaux01.dbf
input datafile fno=00010 name=/u01/app/oracle/oradata/test/ifan
input datafile fno=00002 name=/u01/app/oracle/oradata/test/undotbs01.dbf
input datafile fno=00007 name=/u01/app/oracle/oradata/test/taker
input datafile fno=00009 name=/u01/app/oracle/oradata/test/testing1
input datafile fno=00005 name=/u01/app/oracle/oradata/test/brokerdb
input datafile fno=00006 name=/u01/app/oracle/oradata/test/moneio
input datafile fno=00011 name=/u01/app/oracle/oradata/test/web1
input datafile fno=00012 name=/u01/app/oracle/oradata/test/e1
input datafile fno=00013 name=/u01/app/oracle/oradata/test/ind1
channel ORA_DISK_1: backup set complete, elapsed time: 00:06:57
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
including current control file in backupset
including current SPFILE in backupset
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:02
Finished backup at 09-MAY-08
and when i do the following query
select * from v$database_block_corruption in sqlplus
then there was no row
so it means there is no logical corruption, but when i am looking at alert log file it is giving following lines
Fri May 9 10:14:04 2008
Errors in file /u01/app/oracle/admin/test/udump/test_ora_6606.trc:
Fri May 9 10:14:04 2008
Errors in file /u01/app/oracle/admin/test/udump/test_ora_6606.trc:
Fri May 9 10:14:04 2008
Errors in file /u01/app/oracle/admin/test/udump/test_ora_6606.trc
and in above trace file following contents
/u01/app/oracle/admin/test4/udump/test_ora_6606.trc
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1
System name: Linux
Node name: test
Release: 2.6.18-5-686
Version: #1 SMP Wed Oct 3 00:12:50 UTC 2007
Machine: i686
Instance name: test
Redo thread mounted by this instance: 1
Oracle process number: 61
Unix process pid: 6606, image: oracle@test (TNS V1-V3)
*** 2008-05-09 10:14:04.093
*** ACTION NAME:(0000040 STARTED19) 2008-05-09 10:14:04.071
*** MODULE NAME:(backup full datafile) 2008-05-09 10:14:04.071
*** SERVICE NAME:(SYS$USERS) 2008-05-09 10:14:04.071
*** SESSION ID:(91.40318) 2008-05-09 10:14:04.071
Is it normal, why the in alert file it is saying that Error in.
And it did not create any backupset in folder of flash recovery but in Enterprise manager it is showing last backup on 09-may-2008, why ?
Regards,

Answer 1

See logical corruption is normally termed as the internal inconsistancy within the block which is not caused by Oracle but by the user.So if you find internal inconsistancy than the best option is to look at the user and ask him to get the values sorted out.If the internal inconsistancy is some thig like index fragmentation sort of things or index entry pointing to a null rowid than they are termed as the logical corruption and they should not impact your normal as he data is already there and there is no issue in reading the block as such.
The term "corrupted blocks" I would call both in the tables and backup for those data blocks which are unreadable by Oracle which actualy is Physical corruption.
If i am doing the checking at 2:00 am, does it take more than two hours.I didnt understand this.
what can we do for Physical corruptionThis will need the block to be recovered with the Block Recover command of RMAN and a good backup.Read about it here,
http://download.oracle.com/docs/cd/B19306_01/backup.102/b14194/rcmsynta010.htm
About the Logical and Physical corruption checks , check here
http://download-west.oracle.com/docs/cd/B19306_01/backup.102/b14191/rcmconc1012.htm
Aman....