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ORA-01578エラはOracleによく現れる物理的なベッドブロックエラ(Corruption)で、10gから完全なバックアップとアーカイブログを持っている場合に、blockrecover/recoverコマンドでそのベッドブロックをオンラインでリカバリできる。その前提はデータブロックを含むトラックがまだ使用可能である。
以下の内容はバックアップなしにORA-01578エラを解決する例である。一部ベッドブロックのデータがなくす。：
SQL> exec DBMS_STATS.GATHER_DATABASE_STATS;
BEGIN DBMS_STATS.GATHER_DATABASE_STATS; END;
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 4, block # 870212)
ORA-01110: data file 4:
‘/s01/oradata/G10R25/datafile/o1_mf_users_7ch7d4nx_.dbf’
ORA-06512: at “SYS.DBMS_STATS”, line 15188
ORA-06512: at “SYS.DBMS_STATS”, line 15530
ORA-06512: at “SYS.DBMS_STATS”, line 15674
ORA-06512: at “SYS.DBMS_STATS”, line 15638
ORA-06512: at line 1
RMAN blockreocverコマンドで物理的なベッドブロックを修復する：
RMAN> blockrecover datafile 4 block 870212;
Starting blockrecover at 08-NOV-12
channel ORA_DISK_1: restored block(s) from backup piece 1
piece handle=/s01/flash_recovery_area/G10R25/backupset/2012_08_06/o1_mf_nnndf_TAG20120806T075500_81zd4njn_.bkp tag=TAG20120806T075500
channel ORA_DISK_1: block restore complete, elapsed time: 00:01:16
starting media recovery
archive log thread 1 sequence 467 is already on disk as file /s01/flash_recovery_area/G10R25/archivelog/2012_10_31/o1_mf_1_467_893571cm_.arc
archive log thread 1 sequence 468 is already on disk as file /s01/flash_recovery_area/G10R25/archivelog/2012_10_31/o1_mf_1_468_893pc84l_.arc
archive log thread 1 sequence 469 is already on disk as file /s01/flash_recovery_area/G10R25/archivelog/2012_11_01/o1_mf_1_469_894zsbym_.arc
archive log thread 1 sequence 470 is already on disk as file /s01/flash_recovery_area/G10R25/archivelog/2012_11_01/o1_mf_1_470_896b944y_.arc
4_.arc
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of blockrecover command at 11/08/2012 06:19:40
RMAN-06053: unable to perform media recovery because of missing log
RMAN-06025: no backup of log thread 1 seq 466 lowscn 27762151 found to restore
RMAN-06025: no backup of log thread 1 seq 465 lowscn 27762145 found to restore
RMAN-06025: no backup of log thread 1 seq 464 lowscn 27762142 found to restore
必要なアーカイブログがないから。ブロックをリカバリすることが失敗した。
まずはデータブロックがどれのセグメントに属しているかを確認する。けどテーブルデータの場合に、ベッドブロックのデータをなくなる：
SQL> col tablespace_name for a20
SQL> col segment_type for a10
SQL> col segment_name for a20
SQL> col owner for a8
SQL> SELECT tablespace_name, segment_type, owner, segment_name
2 FROM dba_extents
3 WHERE file_id = &fileid
4 and &blockid between block_id AND block_id + blocks – 1;
Enter value for fileid: 4
old 3: WHERE file_id = &fileid
new 3: WHERE file_id = 4
Enter value for blockid: 870212
old 4: and &blockid between block_id AND block_id + blocks – 1
new 4: and 870212 between block_id AND block_id + blocks – 1
TABLESPACE_NAME SEGMENT_TY OWNER SEGMENT_NAME
——————– ———- ——– ——————–
USERS TABLE SYS CORRUPT_ME
SQL> select count(*) from CORRUPT_ME;
select count(*) from CORRUPT_ME
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 4, block # 870212)
ORA-01110: data file 4:
‘/s01/oradata/G10R25/datafile/o1_mf_users_7ch7d4nx_.dbf’
SQL> analyze table corrupt_me validate structure;
analyze table corrupt_me validate structure
*
ERROR at line 1:
ORA-01498: block check failure – see trace file
SQL> oradebug setmypid
Statement processed.
SQL> oradebug tracefile_name
/s01/admin/G10R25/udump/g10r25_ora_19749.trc
Corrupt block relative dba: 0x010d4744 (file 4, block 870212)
Bad header found during buffer read
Data in bad block:
type: 6 format: 2 rdba: 0x000d4744
last change scn: 0x0000.00000000 seq: 0xff flg: 0x04
spare1: 0x0 spare2: 0x0 spare3: 0x0
consistency value in tail: 0x000006ff
check value in block header: 0x6323
computed block checksum: 0x0
Reread of rdba: 0x010d4744 (file 4, block 870212) found same corrupted data
*** 2012-11-08 06:23:12.564
table scan: segment: file# 4 block# 870211
skipping corrupt block file# 4 block# 870212
*** 2012-11-08 06:23:36.955
table scan: segment: file# 4 block# 870211
skipping corrupt block file# 4 block# 870212
skipping corrupted block at rdba: 0x010d4744
次は10231 level 10トランザクションでORA-01578エラを避ける例で、もとのベッドブロックのテーブルをコピする：
SQL> alter session set events ‘10231 trace name context forever,level 10’;
Session altered.
SQL> select count(*) from CORRUPT_ME;
COUNT(*)
———-
50857
SQL> create table corrupt_me_copy tablespace users as select * from CORRUPT_ME;
Table created.
SQL> analyze table corrupt_me_copy validate structure;
Table analyzed.
後でテーブルを古いテーブルの名で再命名して、インディクスを再構造すればいい：
SQL> alter table corrupt_me rename to corrupt_me_copy1;
Table altered.
SQL> alter table corrupt_me_copy rename to corrupt_me;
Table altered.
SQL> rebuild indexs
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