Fractured block found during backing up datafile

It happens while taking RMAN backup.
If RMAN is unable to get a consistent image of the block it would report errors saying found fractured block while trying to backup that block. RMAN would however retry again and see if it is now able to get the consistent image of the block. we can see in Alert log file that it has found a valid block.

Please note it’s recommended to run the RMAN backup when the load on the database is less.

RMAN reads Oracle blocks from disk. If it finds that the block is fractured,  which means it is being actively used, it performs a reread of the block. If that fails again then the block is assumed to be corrupt.

cause: RMAN backups of datafile are being performed while the datafile is involved in heavy I/O.

fix: Run the backups when the tablespace has less I/O activity.

Alert log:
Thu Sep 05 21:04:54 2013
Hex dump of (file 5, block 259976) in trace file /sw/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_5786.trc
Corrupt block relative dba: 0x0143f788 (file 5, block 259976)
Fractured block found during backing up datafile
Data in bad block:
type: 40 format: 2 rdba: 0x0143f788
last change scn: 0x056f.3979ebee seq: 0x2 flg: 0x04
spare1: 0x0 spare2: 0x0 spare3: 0x0
consistency value in tail: 0x40a82802
check value in block header: 0x83eb
computed block checksum: 0xaa46

Reread of blocknum=259976, file=/data/oracle/oradata/orcl/users01.dbf. found valid data

No comments:

Post a Comment