Hello,
Firstly - I have problem on non-production database 11.2.0.1.0, so I am not deeply worried about data. But I need to understand what happened with database backups and how to prevent such things in future.
So - I have EM scheduled weekly full backup and daily incremental backups. Later there was problem with hardware and some corrupted blocks in database were found. The weekly backup ran without error and obsolete backups were deleted. Now it is not possible to "recover corruption list" because no backup without corruption exists (RMAN-06023: no backup or copy of datafile 6 found to restore). I am not worried about the lost data, but I need to find out how come the backup contains corrupted block.
I have checked the data file using dbv utility
DBVERIFY - Verification starting : FILE = /opt/oracle/oradata/orcl/users03.dbf
DBV-00200: Block, DBA 27525766, already marked corrupt
csc(0x0001.7b01729f) higher than block scn(0x0000.00000000)
Page 2359942 failed with check code 6054
DBVERIFY - Verification complete
Total Pages Examined : 3840000
Total Pages Processed (Data) : 453896
Total Pages Failing (Data) : 1
Total Pages Processed (Index): 2959104
Total Pages Failing (Index): 0
Total Pages Processed (Other): 424025
Total Pages Processed (Seg) : 0
Total Pages Failing (Seg) : 0
Total Pages Empty : 2975
Total Pages Marked Corrupt : 1
Total Pages Influx : 0
Total Pages Encrypted : 0
Highest block SCN : 2156227446 (1.2156227446)
As you can see the datafile 6 - user03.dbf has errors. Also backups now contain errors.
1) So how is it possible that the EM scheduled backup ran without problems and the backup now contains corrupted blocks. How to prevent this in future ? I know there is setting MAXCORRUPT. How can I check its current value ? How can I configure it using EM scheduled backups ?
2) Secondly, meanwhile I studied the RMAN commands. So I have suspended EM backup jobs, and executed follwing command. And backup ran without error again. How is this possible, if data file users06.dbf has corrupted block ?
Thanks !
RMAN> run {
set MAXCORRUPT for datafile 6 to 0;
backup as compressed backupset datafile 6;
}
2> 3> 4>
executing command: SET MAX CORRUPT
Starting backup at 07-NOV-12
using channel ORA_DISK_1
using channel ORA_DISK_2
using channel ORA_DISK_3
using channel ORA_DISK_4
using channel ORA_DISK_5
channel ORA_DISK_1: starting compressed full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00006 name=/opt/oracle/oradata/orcl/users03.dbf
channel ORA_DISK_1: starting piece 1 at 07-NOV-12
channel ORA_DISK_1: finished piece 1 at 07-NOV-12
piece handle=/opt/oraBackup/rman/nrnpo0sg_1_1 tag=TAG20121107T200120 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 01:13:05
Finished backup at 07-NOV-12
Starting Control File and SPFILE Autobackup at 07-NOV-12
piece handle=/opt/oraBackup/rman/c-1253245572-20121107-03 comment=NONE
Finished Control File and SPFILE Autobackup at 07-NOV-12