在上一篇中写道了文件系统的库,在进行异常恢复前的备份方法（Oracle异常恢复前备份保护现场建议—FileSystem环境）,对于asm库,因为asm 里面的数据文件无法直接dd文件头,因此备份方式也有所改变.对于asm是mount,但是数据库不能打开,使用rman或者asm的cp命令全部备份数据文件也来不及或者空间不足,这样的情况下,你可以考虑使用rman或者cp命令备份控制文件和system表空间文件,cp命令备份redo,dd命令备份文件头,来完成asm情况下数据库异常恢复前备份

控制文件备份
11.2及其以后版本使用asmcmd cp命令处理

select 'asmcmd cp '||name||' &&backup_dir/' from v$datafile where ts#=0
union all
select 'asmcmd cp '||name||' &&backup_dir/crontrofile_'||rownum||'.ctl' from v$controlfile
union all
select 'asmcmd cp '||member||' &&backup_dir/'||thread#||'_'||a.group#||'_'||sequence#||'_'||substr(member,
instr(member,'/',-1)+1)  FROM v$log a, v$logfile b WHERE a.group# = B.GROUP#;

其他版本使用rman命令处理

--rman备份控制文件(/tmp目录自己修改)
copy current controlfile to '/tmp/ctl.ctl';
--rman备份system表空间
select 'copy datafile '||file#||' to ''&backup_dir/system_'||file#||'.dbf'';'
from v$datafile where ts#=0;
--redo无法直接备份

备份文件头

[grid@xifenfei ~]$ ss
SQL*Plus: Release 11.2.0.4.0 Production on Fri May 1 04:15:18 2015
Copyright (c) 1982, 2013, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Automatic Storage Management option
SQL> set lines 150
SQL> select 'dd if='||c.PATH_KFDSK||' of=&&backup_path/'||a.GROUP_KFFXP||'_'||a.disk_kffxp||'_'||
  2  b.NUMBER_KFFIL||'.asm count=1 bs='|| d.AUSIZE_KFGRP||' skip='||a.au_kffxp backup_dd_cmd
  3   FROM x$kffxp a, X$KFFIL  b,X$KFDSK c,X$KFGRP d  WHERE
  4  a.GROUP_KFFXP=b.GROUP_KFFIL
  5  and a.NUMBER_KFFXP=b.NUMBER_KFFIL
  6  and b.FTYPE_KFFIL in(2,12)
  7  and b.NUMBER_KFFIL>255
  8  and a.xnum_kffxp=0
  9  and a.GROUP_KFFXP=c.GRPNUM_KFDSK
 10  and a.disk_kffxp=c.NUMBER_KFDSK
 11  and a.GROUP_KFFXP=d.NUMBER_KFGRP;
Enter value for backup_path: /tmp
old   1: select 'dd if='||c.PATH_KFDSK||' of=&&backup_path/'||a.GROUP_KFFXP||'_'||a.disk_kffxp||'_'||
new   1: select 'dd if='||c.PATH_KFDSK||' of=/tmp/'||a.GROUP_KFFXP||'_'||a.disk_kffxp||'_'||
BACKUP_DD_CMD
------------------------------------------------------------------------------------------------------------------
dd if=/dev/asm-disk1 of=/tmp/1_0_256.asm count=1 bs=1048576 skip=29
dd if=/dev/asm-disk2 of=/tmp/1_1_257.asm count=1 bs=1048576 skip=404
dd if=/dev/asm-disk2 of=/tmp/1_1_258.asm count=1 bs=1048576 skip=641
dd if=/dev/asm-disk1 of=/tmp/1_0_259.asm count=1 bs=1048576 skip=648
dd if=/dev/asm-disk3 of=/tmp/2_0_256.asm count=1 bs=1048576 skip=51

还原文件头

SQL> set lines 150
SQL> select 'dd of='||c.PATH_KFDSK||' if=&&backup_path/'||a.GROUP_KFFXP||'_'||a.disk_kffxp||
  2  '_'||b.NUMBER_KFFIL||'.asm count=1 conv=notrunc bs='|| d.AUSIZE_KFGRP||' seek='||a.au_kffxp restore_dd_cmd
  3   FROM x$kffxp a, X$KFFIL  b,X$KFDSK c,X$KFGRP d  WHERE
  4  a.GROUP_KFFXP=b.GROUP_KFFIL
  5  and a.NUMBER_KFFXP=b.NUMBER_KFFIL
  6  and b.FTYPE_KFFIL in(2,12)
  7  and b.NUMBER_KFFIL>255
  8  and a.xnum_kffxp=0
  9  and a.GROUP_KFFXP=c.GRPNUM_KFDSK
 10  and a.disk_kffxp=c.NUMBER_KFDSK
 11  and a.GROUP_KFFXP=d.NUMBER_KFGRP;
old   1: select 'dd of='||c.PATH_KFDSK||' if=&&backup_path/'||a.GROUP_KFFXP||'_'||a.disk_kffxp||
new   1: select 'dd of='||c.PATH_KFDSK||' if=/tmp/'||a.GROUP_KFFXP||'_'||a.disk_kffxp||
RESTORE_DD_CMD
-----------------------------------------------------------------------------------------------------------------
dd of=/dev/asm-disk1 if=/tmp/1_0_256.asm count=1 conv=notrunc bs=1048576 seek=29
dd of=/dev/asm-disk2 if=/tmp/1_1_257.asm count=1 conv=notrunc bs=1048576 seek=404
dd of=/dev/asm-disk2 if=/tmp/1_1_258.asm count=1 conv=notrunc bs=1048576 seek=641
dd of=/dev/asm-disk1 if=/tmp/1_0_259.asm count=1 conv=notrunc bs=1048576 seek=648
dd of=/dev/asm-disk3 if=/tmp/2_0_256.asm count=1 conv=notrunc bs=1048576 seek=51
SQL>

备份还原文件头测试–通过测试证明该方法备份文件头是ok的
关闭数据库,使用dd备份文件头

[oracle@xifenfei ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Fri May 1 04:21:49 2015
Copyright (c) 1982, 2013, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, Automatic Storage Management, OLAP, Data Mining
and Real Application Testing options
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.

dul查看当前dbname值为XIFENFEI

[oracle@xifenfei dul]$ ./dul
Data UnLoader: 10.2.0.6.5 - Internal Only - on Fri May  1 04:37:43 2015
with 64-bit io functions
Copyright (c) 1994 2015 Bernard van Duijnen All rights reserved.
 Strictly Oracle Internal Use Only
Disk group DATA, dul group_cid 0
Discovered disk /dev/asm-disk1 as diskgroup DATA, disk number 0 size 3922 Mb File1 starts at 2, dul_disk_cid 0
Discovered disk /dev/asm-disk2 as diskgroup DATA, disk number 1 size 3922 Mb without File1 meta data, dul_disk_cid 1
Disk group XIFENFEI, dul group_cid 1
Discovered disk /dev/asm-disk3 as diskgroup XIFENFEI, disk number 0 size 4439 Mb File1 starts at 2, dul_disk_cid 2
DUL: Warning: Dictionary cache DC_ASM_EXTENTS is empty
Probing for attributes in File9, the attribute directory, for disk group DATA
attribute name "_extent_sizes", value "1 4 16"
attribute name "_extent_counts", value "20000 20000 2147483647"
Oracle data file size 775954432 bytes, block size 8192
Found db_id = 1495013434
Found db_name = XIFENFEI   <-----db name
DUL: Error: Filedir block not allocated, file does not exist
DUL: Error: Could not load asm meta data for group XIFENFEI file 9
Probing for filenames in File6, the alias directory, for disk group XIFENFEI
+XIFENFEI/XIFENFEI/DATAFILE/XIFENFEI.256.878397315
Probing for database datafiles in File1, the file directory,  for disk group XIFENFEI
File 256 datafile size 104865792, block size 8192
Disk group XIFENFEI has one file of type datafile

使用dd备份1文件头

[oracle@xifenfei tmp]$ dd if=/dev/asm-disk1 of=/tmp/1_0_256.asm count=1 bs=1048576 skip=29
1+0 records in
1+0 records out
1048576 bytes (1.0 MB) copied, 0.0168209 seconds, 62.3 MB/s

尝试把dbname从XIFENFEI修改为ORCL

SQL> select dump('XIFENFEI',16) from dual;
DUMP('XIFENFEI',16)
-------------------------------------
Typ=96 Len=8: 58,49,46,45,4e,46,45,49
SQL> SELECT DUMP('ORCL',16) FROM DUAL;
DUMP('ORCL',16)
-------------------------
Typ=96 Len=4: 4f,52,43,4c
SQL>

bbed修改XIFENFEI为ORCL

[oracle@xifenfei tmp]$ bbed filename='/tmp/1_0_256.asm' mode=edit
Password:
BBED: Release 2.0.0.0.0 - Limited Production on Fri May 1 04:24:06 2015
Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.
************* !!! For Oracle Internal Use only !!! ***************
BBED> set blocksize 8192
        BLOCKSIZE       8192
BBED> set block 1
        BLOCK#          1
BBED> map
 File: /tmp/1_0_256.asm (0)
 Block: 1                                     Dba:0x00000000
------------------------------------------------------------
 Data File Header
 struct kcvfh, 860 bytes                    @0
 ub4 tailchk                                @8188
BBED> p kcvfhhdr
struct kcvfhhdr, 76 bytes                   @20
   ub4 kccfhswv                             @20       0x00000000
   ub4 kccfhcvn                             @24       0x0b200400
   ub4 kccfhdbi                             @28       0x591c183a
   text kccfhdbn[0]                         @32      X
   text kccfhdbn[1]                         @33      I
   text kccfhdbn[2]                         @34      F
   text kccfhdbn[3]                         @35      E
   text kccfhdbn[4]                         @36      N
   text kccfhdbn[5]                         @37      F
   text kccfhdbn[6]                         @38      E
   text kccfhdbn[7]                         @39      I
BBED> d seek 32
 File: /tmp/1_0_256.asm (0)
 Block: 1                seeks:   32 to   63           Dba:0x00000000
------------------------------------------------------------------------
 58494645 4e464549 12040000 00720100 00200000 01000300 00000000 00000000
 <32 bytes per line>

dd把修改的block还原到asm中

[oracle@xifenfei dul]$ dd of=/dev/asm-disk1 if=/tmp/1_0_256.asm count=1 conv=notrunc bs=1048576 seek=29
1+0 records in
1+0 records out
1048576 bytes (1.0 MB) copied, 0.00253244 seconds, 414 MB/s

dul验证dbname 修改为ORCL成功

[oracle@xifenfei dul]$ ./dul
Data UnLoader: 10.2.0.6.5 - Internal Only - on Fri May  1 04:41:33 2015
with 64-bit io functions
Copyright (c) 1994 2015 Bernard van Duijnen All rights reserved.
 Strictly Oracle Internal Use Only
Disk group DATA, dul group_cid 0
Discovered disk /dev/asm-disk1 as diskgroup DATA, disk number 0 size 3922 Mb File1 starts at 2, dul_disk_cid 0
Discovered disk /dev/asm-disk2 as diskgroup DATA, disk number 1 size 3922 Mb without File1 meta data, dul_disk_cid 1
Disk group XIFENFEI, dul group_cid 1
Discovered disk /dev/asm-disk3 as diskgroup XIFENFEI, disk number 0 size 4439 Mb File1 starts at 2, dul_disk_cid 2
DUL: Warning: Dictionary cache DC_ASM_EXTENTS is empty
Probing for attributes in File9, the attribute directory, for disk group DATA
attribute name "_extent_sizes", value "1 4 16"
attribute name "_extent_counts", value "20000 20000 2147483647"
Oracle data file size 775954432 bytes, block size 8192
Found db_id = 1495013434
Found db_name = ORCL   <----修改后的dbname
DUL: Error: Filedir block not allocated, file does not exist
DUL: Error: Could not load asm meta data for group XIFENFEI file 9
Probing for filenames in File6, the alias directory, for disk group XIFENFEI
+XIFENFEI/XIFENFEI/DATAFILE/XIFENFEI.256.878397315
Probing for database datafiles in File1, the file directory,  for disk group XIFENFEI
File 256 datafile size 104865792, block size 8192
Disk group XIFENFEI has one file of type datafile

对于asm无法mount情况下备份asm disk header
asm磁盘的备份主要是备份磁盘头100M空间,使用dd命令直接备份

set lines 150
set pages 1000
select 'dd if='||path||' of=&asmbackup_dir/'||group_number||'_'||disk_number||'.asm bs=1048576
count=100' from v$asm_disk;

set lines 150
set pages 1000
select 'dd of='||path||' if=&asmbackup_dir/'||group_number||'_'||disk_number||'.asm bs=1048576
count=100 conv=notrunc' from v$asm_disk;

asmlib需要注意把ORCL:替换为/dev/oracleasm/disks/对应目录.

无论是在各种会议上,还是在朋友/网友私下请教Oracle数据库恢复的问题之时,我都强调,如果你没有十足的把握,请你对您的现场进行备份,确保别对现场进行二次损坏。你不能恢复数据库,但绝对不能再次破坏数据库,给二次恢复增加难度.这里对恢复前备份提供一些指导思想和简单脚本,希望对大家有帮助.

哪些文件需要备份
熟悉数据库恢复的朋友可能都情况,Oracle在异常恢复的过程中主要修改的是system表空间里面数据,其他数据文件,redo数据,控制文件(当然由于redo,undo导致其他数据文件内部的block也可能发生改变)。在备份时间,备份空间允许的情况下,是对这些文件全部备份为好

完整备份文件

set lines 150
set pages 10000
select name from v$datafile
union all
select name from v$controlfile
union all
select member from v$logfile;

有些情况下:比如如果全部备份时间过长,备份空间不足等情况下,我们该如何备份,尽量减少因为异常恢复导致对原环境的损坏.备份最核心的system表空间,数据文件头,redo file,control file等数据,由于这个不是简单的拷贝操作,因此在生成备份语句同时,也生成还原语句,切不可生成了备份语句后,无恢复语句,导致后面还原故障现场难度增大.

无法全备情况下linux/unix数据库恢复前备份

set lines 150
set pages 10000
select 'dd if='||name||' of=&&back_dir/'||ts#||'_'||file#||'.dbf bs=1048576 count=10'
from v$datafile where ts#<>0
union all
select 'dd if='||name||' of=&&back_dir/'||ts#||'_'||file#||'.dbf' from v$datafile where ts#=0
union all
select 'dd if='||name||' of=&&back_dir/control0'||rownum||'.ctl' from v$controlfile
union all
select 'dd if='||member||' of=&&back_dir/'||thread#||'_'||a.group#||'_'||sequence#||'_'||substr(member,
instr(member,'/',-1)+1)  FROM v$log a, v$logfile b WHERE a.group# = B.GROUP#;

无法全备情况下linux/unix使用备份还原

set lines 150
set pages 1000
select 'dd of='||name||' if=&&back_dir/'||ts#||'_'||file#||'.dbf bs=1048576 count=10 conv=notrunc'
from v$datafile where ts#<>0
union all
select 'dd if='||name||' if=&&back_dir/'||ts#||'_'||file#||'.dbf' from v$datafile where ts#=0
union all
select 'dd of='||name||' if=&&back_dir/control0'||rownum||'.ctl' from v$controlfile
union all
select 'dd of='||member||' if=&&back_dir/'||thread#||'_'||a.group#||'_'||sequence#||'_'||substr(member,
instr(member,'/',-1)+1)    FROM v$log a, v$logfile b WHERE a.group# = B.GROUP#;

由于win路径斜杠不一样(/和\的区别),因此在无法全备情况下win备份语句

set lines 150
set pages 10000
select 'dd if='||name||' of=&&back_dir\'||ts#||'_'||file#||'.dbf bs=1048576 count=10'
from v$datafile where ts#<>0
union all
select 'dd if='||name||' of=&&back_dir\'||ts#||'_'||file#||'.dbf' from v$datafile where ts#=0
union all
select 'dd if='||name||' of=&&back_dir\control0'||rownum||'.ctl' from v$controlfile
union all
select 'dd if='||member||' of=&&back_dir\'||thread#||'_'||a.group#||'_'||sequence#||'_'||substr(member,
instr(member,'\',-1)+1)   FROM v$log a, v$logfile b WHERE a.group# = B.GROUP#;

在无法全备情况下win还原语句

set lines 150
set pages 1000
select 'dd of='||name||' if=&&back_dir\'||ts#||'_'||file#||'.dbf bs=1048576 count=10 conv=notrunc'
from v$datafile where ts#<>0
union all
select 'dd if='||name||' if=&&back_dir\'||ts#||'_'||file#||'.dbf' from v$datafile where ts#=0
union all
select 'dd of='||name||' if=&&back_dir\control0'||rownum||'.ctl' from v$controlfile
union all
select 'dd of='||member||' if=&&back_dir\'||thread#||'_'||a.group#||'_'||sequence#||'_'||substr(member,
instr(member,'\',-1)+1)    FROM v$log a, v$logfile b WHERE a.group# = B.GROUP#;

这里提供win环境下dd命令程序win环境dd命令工具

备注:对于asm情况异常情况恢复,备份情况请不要参考该文章,具体请见后续文章,具体见Oracle异常恢复前备份保护现场建议—ASM环境