Controlfile 重建控制文件 noresetlogs, resetlogs..

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当数据库当前的Redo Log都可用时（no matter 断电或者shutdown abort），可以通过 noresetlogs 参数重建控制文件，此时 Oracle能够从日志文件中读取Redo信息 （同样的，控制文件也能够从数据文件中获得详细的检查点信息），记录到控制文件中，由于Redo中记录的信息足以重演所有提交成功的事物，所以能够实现完全恢复，成功打开数据库， 这时的数据库就如同进行了一次断电之后的实例恢复，数据没有损失，重做日志可以继续向前写入 。 CREATE CONTROLFILE REUSE DATABASE "ORCL" NORESETLOGS NOARCHIVELOG 。。。。转储新建的控制文件，可看到 LOG FILE #3是当前的日志文件，而且包含scn等信息。 alter session set events 'immediate trace name CONTROLF level 8' *************************************************************************** LOG FILE RECORDS *************************************************************************** (size = 72, compat size = 72, section max = 16, section in-use = 3, last-recid= 0, old-recno = 0, last-recno = 0) (extent = 1, blkno = 10, numrecs = 16) LOG FILE #1: name #5: E:\ORACLE\ORADATA\ORCL\ONLINELOG\O1_MF_1_G23756JL_.LOG name #6: E:\ORACLE\FAST_RECOVERY_AREA\ORCL\ORCL\ONLINELOG\O1_MF_1_G2375PPY_.LOG Thread 1 redo log links: forward: 2 backward: 0 siz: 0x64000 seq: 0x00000010 hws: 0x3 bsz: 512 nab: 0x16c flg: 0x0 dup: 2 Archive links: fwrd: 0 back: 0 Prev scn: 0x0000000000000000 Low scn: 0x000000000024df24 01/01/2019 17:09:28 Next scn: 0x000000000024e27c 01/01/2019 17:43:47 LOG FILE #2: name #3: E:\ORACLE\ORADATA\ORCL\ONLINELOG\O1_MF_2_G23756JT_.LOG name #4: E:\ORACLE\FAST_RECOVERY_AREA\ORCL\ORCL\ONLINELOG\O1_MF_2_G2375PQF_.LOG Thread 1 redo log links: forward: 3 backward: 1 siz: 0x64000 seq: 0x00000011 hws: 0x4 bsz: 512 nab: 0x4e05 flg: 0x0 dup: 2 Archive links: fwrd: 0 back: 0 Prev scn: 0x000000000024df24 Low scn: 0x000000000024e27c 01/01/2019 17:43:47 Next scn: 0x0000000000267e7b 01/01/2019 20:59:36 LOG FILE #3: name #1: E:\ORACLE\ORADATA\ORCL\ONLINELOG\O1_MF_3_G23756K3_.LOG name #2: E:\ORACLE\FAST_RECOVERY_AREA\ORCL\ORCL\ONLINELOG\O1_MF_3_G2375PQ6_.LOG Thread 1 redo log links: forward: 0 backward: 2 siz: 0x64000 seq: 0x00000012 hws: 0x2 bsz: 512 nab: 0xffffffff flg: 0xa dup: 2 Archive links: fwrd: 0 back: 0 Prev scn: 0x000000000024e27c Low scn: 0x0000000000267e7b 01/01/2019 20:59:36 Next scn: 0xffffffffffffffff 01/01/1988 00:00:00 如果用resetlogs重建控制文件，在恢复时就需要 RECOVER DATABASE USING BACKUP CONTROLFILE CREATE CONTROLFILE REUSE DATABASE "ORCL" RESETLOGS NOARCHIVELOG MAXLOGFILES 16 MAXLOGMEMBERS 3 MAXDATAFILES 1024 。。。。这时查看转储的控制文件，scn是0 *************************************************************************** LOG FILE RECORDS *************************************************************************** (size = 72, compat size = 72, section max = 16, section in-use = 3, last-recid= 0, old-recno = 0, last-recno = 0) (extent = 1, blkno = 10, numrecs = 16) LOG FILE #1: name #5: E:\ORACLE\ORADATA\ORCL\ONLINELOG\O1_MF_1_G23756JL_.LOG name #6: E:\ORACLE\FAST_RECOVERY_AREA\ORCL\ORCL\ONLINELOG\O1_MF_1_G2375PPY_.LOG Thread 1 redo log links: forward: 2 backward: 0 siz: 0x64000 seq: 0x00000000 hws: 0x0 bsz: 512 nab: 0x0 flg: 0x1 dup: 2 Archive links: fwrd: 0 back: 0 Prev scn: 0x0000000000000000 Low scn: 0x0000000000000000 01/01/1988 00:00:00 Next scn: 0x0000000000000000 01/01/1988 00:00:00 SQL> RECOVER DATABASE USING BACKUP CONTROLFILE UNTIL CANCEL ; ORA-00279: ?? 2829520 (? 01/01/2019 22:22:52 ??) ???? 1 ???? ORA-00289: ??: E:\ORACLE\FAST_RECOVERY_AREA\ORCL\ORCL\ARCHIVELOG\2019_01_01\O1_MF_1_2_%U_.ARC ORA-00280: ?? 2829520 (???? 1) ??? #2 ? 指定日志: {<RET>=suggested | filename | AUTO | CANCEL} E:\oracle\oradata\ORCL\ONLINELOG\O1_MF_2_G23756JT_.LOG （如果当前redo日志在，不需要指定日志文件，选cancel会自动media recovery。这里测试了把日志文件都移走，选cancel的话， open resetlogs会出错，提示需要介质恢复。）已应用的日志。完成介质恢复。 SQL> alter database open resetlogs ; 数据库已更改。再查看转储的控制文件，logfile2,3 scn是0，到v$log能看到状态是unused. *************************************************************************** LOG FILE RECORDS *************************************************************************** (size = 72, compat size = 72, section max = 16, section in-use = 3, last-recid= 9, old-recno = 0, last-recno = 0) (extent = 1, blkno = 10, numrecs = 16) LOG FILE #1: name #5: E:\ORACLE\ORADATA\ORCL\ONLINELOG\O1_MF_1_G23756JL_.LOG name #6: E:\ORACLE\FAST_RECOVERY_AREA\ORCL\ORCL\ONLINELOG\O1_MF_1_G2375PPY_.LOG Thread 1 redo log links: forward: 2 backward: 0 siz: 0x64000 seq: 0x00000001 hws: 0x3 bsz: 512 nab: 0xffffffff flg: 0x8 dup: 2 Archive links: fwrd: 0 back: 0 Prev scn: 0x0000000000000000 Low scn: 0x000000000029a3d3 01/01/2019 22:15:44 Next scn: 0xffffffffffffffff 01/01/1988 00:00:00 LOG FILE #2: name #3: E:\ORACLE\ORADATA\ORCL\ONLINELOG\O1_MF_2_G23756JT_.LOG name #4: E:\ORACLE\FAST_RECOVERY_AREA\ORCL\ORCL\ONLINELOG\O1_MF_2_G2375PQF_.LOG Thread 1 redo log links: forward: 3 backward: 1 siz: 0x64000 seq: 0x00000000 hws: 0x2 bsz: 512 nab: 0x2 flg: 0x1 dup: 2 Archive links: fwrd: 0 back: 0 Prev scn: 0x0000000000000000 Low scn: 0x0000000000000000 01/01/1988 00:00:00 Next scn: 0x0000000000000000 01/01/1988 00:00:00 resetlogs重建控制文件恢复时，控制文件没有redo信息，rman怎么知道恢复到哪？ 答案就在数据文件头的RBA(Redo Byte Address) ，RBA包含了日志文件的序列号(log sequence)