{"id":11008,"date":"2018-03-17T18:39:02","date_gmt":"2018-03-17T17:39:02","guid":{"rendered":"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/"},"modified":"2023-06-09T16:54:59","modified_gmt":"2023-06-09T14:54:59","slug":"automatic-block-media-recovery-in-a-dataguard","status":"publish","type":"post","link":"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/","title":{"rendered":"Automatic Block Media Recovery in a DataGuard"},"content":{"rendered":"

By Mouhamadou Diaw<\/strong><\/p>\n

With Oracle 12.2, in a Data Guard environment corrupted data blocks can be automatically replaced with uncorrupted copies of those blocks.
\nThere are just some requirements:
\n\u2022 The physical standby database must be operating in real-time query mode, which requires an Oracle Active Data Guard license.
\n\u2022 The physical standby database must be running real-time apply.
\nAutomatic block media recovery works in two directions depending on whether the corrupted blocks are encountered on the primary or on the standby.
\nThis recovery can happen if corrupted data are encountered in the primary database or in the secondary database.
\nIn this blog we are going to see how this feature works.
\nBelow the configuration we are using<\/p>\n

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\n
\n
DGMGRL> show configuration;<\/code><\/div>\n
<\/div>\n
Configuration - ORCL_DR<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Protection Mode: MaxAvailability<\/code><\/div>\n
\u00a0\u00a0<\/code>Members:<\/code><\/div>\n
\u00a0\u00a0<\/code>ORCL_SITE\u00a0 - <\/code>Primary<\/code> database<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ORCL_SITE1 - Physical standby <\/code>database<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ORCL_SITE2 - Physical standby <\/code>database<\/code><\/div>\n
<\/div>\n
Fast-Start Failover: DISABLED<\/code><\/div>\n
<\/div>\n
Configuration Status:<\/code><\/div>\n
SUCCESS\u00a0\u00a0 (status updated 19 seconds ago)<\/code><\/div>\n
<\/div>\n
DGMGRL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

We can verifiy the status of our databases<\/p>\n

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\n
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DGMGRL> show <\/code>database<\/code>\u00a0 'ORCL_SITE'<\/code> ;<\/code><\/div>\n
<\/div>\n
Database<\/code> - ORCL_SITE<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Role:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/code>PRIMARY<\/code><\/div>\n
\u00a0\u00a0<\/code>Intended State:\u00a0\u00a0\u00a0\u00a0 TRANSPORT-<\/code>ON<\/code><\/div>\n
\u00a0\u00a0<\/code>Instance(s):<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ORCL<\/code><\/div>\n
<\/div>\n
Database<\/code> Status:<\/code><\/div>\n
SUCCESS<\/code><\/div>\n
<\/div>\n
DGMGRL> show <\/code>database<\/code>\u00a0 'ORCL_SITE1'<\/code> ;<\/code><\/div>\n
<\/div>\n
Database<\/code> - ORCL_SITE1<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Role:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 PHYSICAL STANDBY<\/code><\/div>\n
\u00a0\u00a0<\/code>Intended State:\u00a0\u00a0\u00a0\u00a0 APPLY-<\/code>ON<\/code><\/div>\n
\u00a0\u00a0<\/code>Transport Lag:\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds (computed 1 <\/code>second<\/code> ago)<\/code><\/div>\n
\u00a0\u00a0<\/code>Apply Lag:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds (computed 1 <\/code>second<\/code> ago)<\/code><\/div>\n
\u00a0\u00a0<\/code>Average Apply Rate: 5.00 KByte\/s<\/code><\/div>\n
\u00a0\u00a0<\/code>Real<\/code> Time<\/code> Query:\u00a0\u00a0\u00a0 <\/code>ON<\/code><\/div>\n
\u00a0\u00a0<\/code>Instance(s):<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ORCL<\/code><\/div>\n
<\/div>\n
Database<\/code> Status:<\/code><\/div>\n
SUCCESS<\/code><\/div>\n
<\/div>\n
DGMGRL> show <\/code>database<\/code>\u00a0 'ORCL_SITE2'<\/code> ;<\/code><\/div>\n
<\/div>\n
Database<\/code> - ORCL_SITE2<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Role:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 PHYSICAL STANDBY<\/code><\/div>\n
\u00a0\u00a0<\/code>Intended State:\u00a0\u00a0\u00a0\u00a0 APPLY-<\/code>ON<\/code><\/div>\n
\u00a0\u00a0<\/code>Transport Lag:\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds (computed 1 <\/code>second<\/code> ago)<\/code><\/div>\n
\u00a0\u00a0<\/code>Apply Lag:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds (computed 1 <\/code>second<\/code> ago)<\/code><\/div>\n
\u00a0\u00a0<\/code>Average Apply Rate: 4.00 KByte\/s<\/code><\/div>\n
\u00a0\u00a0<\/code>Real<\/code> Time<\/code> Query:\u00a0\u00a0\u00a0 <\/code>ON<\/code><\/div>\n
\u00a0\u00a0<\/code>Instance(s):<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ORCL<\/code><\/div>\n
<\/div>\n
Database<\/code> Status:<\/code><\/div>\n
SUCCESS<\/code><\/div>\n
<\/div>\n
DGMGRL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

The feature works for any protection mode, but in our case the tests are done with a MaxAvailability mode<\/p>\n

If corrupt data blocks are on the primary database, then the primary automatically searches for good copies of those blocks on a standby and, if they are found, has them shipped back to the primary.
\nThis only requirement is that the primary requires a LOG_ARCHIVE_DEST_n to the standby. That already should be the case in a Data Guard environment.<\/p>\n

If corrupted block is located on the standby, the standby will automatically request uncorrupted copies of those blocks to the primary. The condition for this mechanism to work is
\n\u2022 The LOG_ARCHIVE_CONFIG parameter is configured with a DG_CONFIG list and a LOG_ARCHIVE_DEST_n parameter is configured for the primary database.
\nor
\n\u2022 The FAL_SERVER parameter is configured and its value contains an Oracle Net service name for the primary database.<\/p>\n

In this demonstration we will simulate data corruption in the primary database. But the scenario is the same for a corrupted blocks at standby side and will work same.
\nFrom the primary we can verify that LOG_ARCHIVE_DEST_n is set.<\/p>\n

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SQL> <\/code>select<\/code> dest_name,DESTINATION,status <\/code>from<\/code> v$archive_dest <\/code>where<\/code> destination <\/code>is<\/code> not<\/code> null<\/code>;<\/code><\/div>\n
<\/div>\n
DEST_NAME\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 DESTINATION\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 STATUS<\/code><\/div>\n
-------------------- ------------------------------ ---------<\/code><\/div>\n
LOG_ARCHIVE_DEST_1\u00a0\u00a0 USE_DB_RECOVERY_FILE_DEST\u00a0\u00a0\u00a0\u00a0\u00a0 VALID<\/code><\/div>\n
LOG_ARCHIVE_DEST_2\u00a0\u00a0 ORCL_SITE1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 VALID<\/code><\/div>\n
LOG_ARCHIVE_DEST_3\u00a0\u00a0 ORCL_SITE2\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 VALID<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

For the demonstration let\u2019s consider a table of user SCOTT in a tablespace mytab<\/p>\n

\n
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SQL> <\/code>select<\/code> table_name,tablespace_name <\/code>from<\/code> dba_tables <\/code>where<\/code> owner=<\/code>'SCOTT'<\/code> and<\/code> table_name=<\/code>'EMPBIS'<\/code>;<\/code><\/div>\n
<\/div>\n
TABLE_NAME\u00a0\u00a0\u00a0\u00a0\u00a0 TABLESPACE_NAME<\/code><\/div>\n
--------------- ------------------------------<\/code><\/div>\n
EMPBIS\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 MYTAB<\/code><\/div>\n
<\/div>\n
SQL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Now let\u2019s identify blocks for the table on the primary and let\u2019s corrupt them.<\/p>\n

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SQL> <\/code>select<\/code> * <\/code>from<\/code> (<\/code>select<\/code> distinct<\/code> dbms_rowid.rowid_block_number(rowid)\u00a0 <\/code>from<\/code> scott.empbis);<\/code><\/div>\n
<\/div>\n
DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)<\/code><\/div>\n
------------------------------------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>131<\/code><\/div>\n
<\/div>\n
SQL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

And then let\u2019s run following command to corrupt corresponding blocks.<\/p>\n

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[oracle@primaserver ORCL]$ <\/code>dd<\/code> of=<\/code>\/u01\/app\/oracle\/oradata\/ORCL\/mytab01<\/code>.dbf bs=8192 seek=131 conv=notrunc count=1 <\/code>if<\/code>=<\/code>\/dev\/zero<\/code><\/div>\n
1+0 records <\/code>in<\/code><\/div>\n
1+0 records out<\/code><\/div>\n
8192 bytes (8.2 kB) copied, 0.000315116 s, 26.0 MB<\/code>\/s<\/code><\/div>\n
[oracle@primaserver ORCL]$<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

In a normal environment, accessing to corrupted data by a SELECT will return errors.
\nBut in our case on the primary if we flush the buffer_cache, and and we do a select on the table, rows are returned without errors.<\/p>\n

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\n
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13:41:18 SQL> <\/code>alter<\/code> system flush buffer_cache;<\/code><\/div>\n
<\/div>\n
System altered.<\/code><\/div>\n
<\/div>\n
13:41:22 SQL> <\/code>select<\/code> * <\/code>from<\/code> scott.empbis;<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>EMPNO ENAME\u00a0\u00a0\u00a0\u00a0\u00a0 JOB\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 MGR HIREDATE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 SAL\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 COMM<\/code><\/div>\n
---------- ---------- --------- ---------- --------- ---------- ----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DEPTNO<\/code><\/div>\n
----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7369 SMITH\u00a0\u00a0\u00a0\u00a0\u00a0 CLERK\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7902 17-<\/code>DEC<\/code>-80\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 800<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>20<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7499 ALLEN\u00a0\u00a0\u00a0\u00a0\u00a0 SALESMAN\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7698 20-FEB-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1600\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 300<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>30<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7521 WARD\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 SALESMAN\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7698 22-FEB-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1250\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 500<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>30<\/code><\/div>\n
<\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>EMPNO ENAME\u00a0\u00a0\u00a0\u00a0\u00a0 JOB\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 MGR HIREDATE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 SAL\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 COMM<\/code><\/div>\n
---------- ---------- --------- ---------- --------- ---------- ----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DEPTNO<\/code><\/div>\n
----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7566 JONES\u00a0\u00a0\u00a0\u00a0\u00a0 MANAGER\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7839 02-APR-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2975<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>20<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7654 MARTIN\u00a0\u00a0\u00a0\u00a0 SALESMAN\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7698 28-SEP-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1250\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1400<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>30<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7698 BLAKE\u00a0\u00a0\u00a0\u00a0\u00a0 MANAGER\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7839 01-MAY-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2850<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>30<\/code><\/div>\n
<\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>EMPNO ENAME\u00a0\u00a0\u00a0\u00a0\u00a0 JOB\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 MGR HIREDATE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 SAL\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 COMM<\/code><\/div>\n
---------- ---------- --------- ---------- --------- ---------- ----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DEPTNO<\/code><\/div>\n
----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7782 CLARK\u00a0\u00a0\u00a0\u00a0\u00a0 MANAGER\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7839 09-JUN-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2450<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>10<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7788 SCOTT\u00a0\u00a0\u00a0\u00a0\u00a0 ANALYST\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7566 19-APR-87\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 3000<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>20<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7839 KING\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 PRESIDENT\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 17-NOV-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 5000<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>10<\/code><\/div>\n
<\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>EMPNO ENAME\u00a0\u00a0\u00a0\u00a0\u00a0 JOB\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 MGR HIREDATE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 SAL\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 COMM<\/code><\/div>\n
---------- ---------- --------- ---------- --------- ---------- ----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DEPTNO<\/code><\/div>\n
----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7844 TURNER\u00a0\u00a0\u00a0\u00a0 SALESMAN\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7698 08-SEP-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1500\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>30<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7876 ADAMS\u00a0\u00a0\u00a0\u00a0\u00a0 CLERK\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7788 23-MAY-87\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1100<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>20<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7900 JAMES\u00a0\u00a0\u00a0\u00a0\u00a0 CLERK\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7698 03-<\/code>DEC<\/code>-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 950<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>30<\/code><\/div>\n
<\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>EMPNO ENAME\u00a0\u00a0\u00a0\u00a0\u00a0 JOB\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 MGR HIREDATE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 SAL\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 COMM<\/code><\/div>\n
---------- ---------- --------- ---------- --------- ---------- ----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DEPTNO<\/code><\/div>\n
----------<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7902 FORD\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ANALYST\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7566 03-<\/code>DEC<\/code>-81\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 3000<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>20<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>7934 MILLER\u00a0\u00a0\u00a0\u00a0 CLERK\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7782 23-JAN-82\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1300<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>10<\/code><\/div>\n
<\/div>\n
<\/div>\n
14 <\/code>rows<\/code> selected.<\/code><\/div>\n
<\/div>\n
13:41:27 SQL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Indeed Oracle automatically recovered corrupted blocks. And in the primary alert log at the same time we can see that a recovery was done.<\/p>\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n
4<\/div>\n
5<\/div>\n
6<\/div>\n
7<\/div>\n
8<\/div>\n
9<\/div>\n
10<\/div>\n
11<\/div>\n
12<\/div>\n
13<\/div>\n
14<\/div>\n
15<\/div>\n
16<\/div>\n
17<\/div>\n
18<\/div>\n
19<\/div>\n
20<\/div>\n
21<\/div>\n<\/td>\n
\n
\n
ALTER SYSTEM: Flushing buffer cache inst=0 container=0 global<\/code><\/div>\n
2018-01-26T13:41:26.540640+01:00<\/code><\/div>\n
Hex dump of (<\/code>file<\/code> 2, block 131) <\/code>in<\/code> trace <\/code>file<\/code> \/u01\/app\/oracle\/diag\/rdbms\/orcl_site\/ORCL\/trace\/ORCL_ora_3359<\/code>.trc<\/code><\/div>\n
<\/div>\n
Corrupt block relative dba: 0x00800083 (<\/code>file<\/code> 2, block 131)<\/code><\/div>\n
Completely zero block found during multiblock buffer <\/code>read<\/code><\/div>\n
<\/div>\n
Reading datafile <\/code>'\/u01\/app\/oracle\/oradata\/ORCL\/mytab01.dbf'<\/code> for<\/code> corruption at rdba: 0x00800083 (<\/code>file<\/code> 2, block 131)<\/code><\/div>\n
Reread (<\/code>file<\/code> 2, block 131) found same corrupt data (no logical check)<\/code><\/div>\n
Automatic block media recovery requested <\/code>for<\/code> (<\/code>file<\/code># 2, block# 131)<\/code><\/div>\n
2018-01-26T13:41:26.545798+01:00<\/code><\/div>\n
Corrupt Block Found<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>TIME STAMP (GMT) = 01<\/code>\/26\/2018<\/code> 13:41:25<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>CONT = 0, TSN = 7, TSNAME = MYTAB<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>RFN = 2, BLK = 131, RDBA = 8388739<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>OBJN = 74352, OBJD = 74352, OBJECT = EMPBIS, SUBOBJECT =<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>SEGMENT OWNER = SCOTT, SEGMENT TYPE = Table Segment<\/code><\/div>\n
2018-01-26T13:41:27.002934+01:00<\/code><\/div>\n
Automatic block media recovery successful <\/code>for<\/code> (<\/code>file<\/code># 2, block# 131)<\/code><\/div>\n
2018-01-26T13:41:27.005015+01:00<\/code><\/div>\n
Automatic block media recovery successful <\/code>for<\/code> (<\/code>file<\/code># 2, block# 131)<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Conclusion:<\/strong>
\nWe have seen, that an active DataGuard environment may help with corrupted data.<\/p>\n","protected":false},"excerpt":{"rendered":"

By Mouhamadou Diaw With Oracle 12.2, in a Data Guard environment corrupted data blocks can be automatically replaced with uncorrupted copies of those blocks. There are just some requirements: \u2022 The physical standby database must be operating in real-time query mode, which requires an Oracle Active Data Guard license. \u2022 The physical standby database must […]<\/p>\n","protected":false},"author":27,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[229],"tags":[1315,999,988],"type_dbi":[],"class_list":["post-11008","post","type-post","status-publish","format-standard","hentry","category-database-administration-monitoring","tag-corrupted-blocks","tag-dataguard","tag-oracle-12-2"],"acf":[],"yoast_head":"\nAutomatic Block Media Recovery in a DataGuard - dbi Blog<\/title>\n<meta name=\"description\" content=\"oracle 12.2, dataguard, corrupted blocks,\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Automatic Block Media Recovery in a DataGuard\" \/>\n<meta property=\"og:description\" content=\"oracle 12.2, dataguard, corrupted blocks,\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/\" \/>\n<meta property=\"og:site_name\" content=\"dbi Blog\" \/>\n<meta property=\"article:published_time\" content=\"2018-03-17T17:39:02+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-06-09T14:54:59+00:00\" \/>\n<meta name=\"author\" content=\"Oracle Team\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Oracle Team\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"6 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/\"},\"author\":{\"name\":\"Oracle Team\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/#\/schema\/person\/66ab87129f2d357f09971bc7936a77ee\"},\"headline\":\"Automatic Block Media Recovery in a DataGuard\",\"datePublished\":\"2018-03-17T17:39:02+00:00\",\"dateModified\":\"2023-06-09T14:54:59+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/\"},\"wordCount\":448,\"commentCount\":1,\"keywords\":[\"corrupted blocks\",\"DataGuard\",\"Oracle 12.2\"],\"articleSection\":[\"Database Administration & Monitoring\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/\",\"url\":\"https:\/\/www.dbi-services.com\/blog\/automatic-block-media-recovery-in-a-dataguard\/\",\"name\":\"Automatic Block Media Recovery in a DataGuard - 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