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[Oracle数据库] [20180413]热备模式相关问题2.txt

发表于 2018-4-26 08:00:00

[20180413]热备模式相关问题2.txt

--//上午测试热备模式相关问题,就是如果打开热备模式,如果中间的归档丢失,oracle在alter database end backup ;时并没有应用日志.
--//虽然热备份模式文件头scn被"冻结",一定在某个地方记录的检查点的scn,这样在执行alter database end backup ;时,写入新的scn
--//这样在恢复时才有可能跳过一些丢失的归档.

--//从某种意义讲,oracle这样设计有一定道理,假设某种情况打开热备模式,由于热备模式中断或者没有完成,忘记结束,如果在某次异常关闭时
--//需要恢复,并需要从"冻结"的scn号开始恢复.
--//测试看看这些相关信息保存在那里.

1.环境:
SCOTT@book> @ ver1
PORT_STRING VERSION BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx 11.2.0.4.0 Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

2.测试1:
SYS@book> alter tablespace tea begin backup ;
Tablespace altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- -------------------------------------------------- ------------------------------
1 13277609065 2018-04-13 09:38:45 7 925702 ONLINE 937 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277634716 2018-04-13 15:02:36 13276257767 925702 ONLINE 309 YES /mnt/ramdisk/book/tea01.dbf TEA

SYS@book> alter tablespace tea end backup ;
Tablespace altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- -------------------------------------------------- ------------------------------
1 13277609065 2018-04-13 09:38:45 7 925702 ONLINE 937 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277634716 2018-04-13 15:02:36 13276257767 925702 ONLINE 310 YES /mnt/ramdisk/book/tea01.dbf TEA

--//数据文件6的scn=13277634716,没有变化,CHECKPOINT_COUNT增加.

3.测试2:
SYS@book> alter tablespace tea begin backup ;
Tablespace altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- -------------------------------------------------- ------------------------------
1 13277609065 2018-04-13 09:38:45 7 925702 ONLINE 937 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277634864 2018-04-13 15:04:47 13276257767 925702 ONLINE 311 YES /mnt/ramdisk/book/tea01.dbf TEA

SYS@book> alter system checkpoint ;
System altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- -------------------------------------------------- ------------------------------
1 13277634878 2018-04-13 15:04:56 7 925702 ONLINE 938 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277634864 2018-04-13 15:04:47 13276257767 925702 ONLINE 312 YES /mnt/ramdisk/book/tea01.dbf TEA

--//虽然数据文件6呃文件头scn被冻结13277634864,但是CHECKPOINT_COUNT依旧还是增加,也就是还是会改动文件头信息.

select 13277634878,trunc(13277634878/power(2,32)) scn_wrap,mod(13277634878,power(2,32)) scn_base from dual
13277634878 SCN_WRAP SCN_BASE SCN_WRAP16 SCN_BASE16
------------ ------------ ------------ ---------- ----------
13277634878 3 392732990 3 1768a13e

SYS@book> @ &r/10to16 392732990
10 to 16 HEX REVERSE16
----------------- -----------------------------------
000000001768a13e 0x3ea16817-00000000

--//通过bbed观察,可以发出检查点信息是记录在文件头中的.

BBED> p dba 6,1 kcvfh.kcvfhbcp.kcvcpscn
struct kcvcpscn, 8 bytes @152
ub4 kscnbas @152 0x1768a13e
ub2 kscnwrp @156 0x0003

SYS@book> alter system checkpoint ;
System altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- ---------------------------------------------------- ------------------------------
1 13277635895 2018-04-13 15:13:16 7 925702 ONLINE 939 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277634864 2018-04-13 15:04:47 13276257767 925702 ONLINE 313 YES /mnt/ramdisk/book/tea01.dbf TEA

SYS@book> @ &r/10to16 13277635895
10 to 16 HEX REVERSE16
----------------- -----------------------------------
000000031768a537 0x37a56817-03000000

BBED> p dba 6,1 kcvfh.kcvfhbcp.kcvcpscn
struct kcvcpscn, 8 bytes @152
ub4 kscnbas @152 0x1768a537
ub2 kscnwrp @156 0x0003

--//可以发现数据文件6kcvfh.kcvfhbcp.kcvcpscn位置也会更新.这样在结束热备模式时,自动更新文件头.

SYS@book> alter tablespace tea end backup ;
Tablespace altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- ---------------------------------------------------- ------------------------------
1 13277635895 2018-04-13 15:13:16 7 925702 ONLINE 939 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277635895 2018-04-13 15:13:16 13276257767 925702 ONLINE 314 YES /mnt/ramdisk/book/tea01.dbf TEA

--//这也就很好解析为什么结束热备模式,从那里更新检查点.另外kcvfh.kcvfhbcp.kcvcpscn,里面的hb可以猜测表示hot backup的意思.

4.测试3:
--//做一个文件头转储看看:
SYS@book> alter tablespace tea begin backup ;
Tablespace altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- ---------------------------------------------------- ------------------------------
1 13277635895 2018-04-13 15:13:16 7 925702 ONLINE 939 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277637553 2018-04-13 15:39:15 13276257767 925702 ONLINE 317 YES /mnt/ramdisk/book/tea01.dbf TEA

SYS@book> alter system checkpoint ;
System altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- ---------------------------------------------------- ------------------------------
1 13277637599 2018-04-13 15:39:56 7 925702 ONLINE 940 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277637553 2018-04-13 15:39:15 13276257767 925702 ONLINE 318 YES /mnt/ramdisk/book/tea01.dbf TEA

select 13277637599,trunc(13277637599/power(2,32)) scn_wrap,mod(13277637599,power(2,32)) scn_base from dual
13277637599 SCN_WRAP SCN_BASE SCN_WRAP16 SCN_BASE16
------------ ------------ ------------ ---------- ----------
13277637599 3 392735711 3 1768abdf

select 13277637553,trunc(13277637553/power(2,32)) scn_wrap,mod(13277637553,power(2,32)) scn_base from dual
13277637553 SCN_WRAP SCN_BASE SCN_WRAP16 SCN_BASE16
------------ ------------ ------------ ---------- ----------
13277637553 3 392735665 3 1768abb1

SYS@book> alter session set events 'immediate trace name FILE_HDRS level 12';
Session altered.

--//检查转储:
DATA FILE #6:
name #10: /mnt/ramdisk/book/tea01.dbf
creation size=5120 block size=8192 status=0xe head=10 tail=10 dup=1
tablespace 7, index=7 krfil=6 prev_file=0
unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00
Checkpoint cnt:318 scn: 0x0003.1768abb1 04/13/2018 15:39:15
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// --> 注这里的信息来之控制文件:http://blog.itpub.net/267265/viewspace-2136766/

Stop scn: 0xffff.ffffffff 04/13/2018 09:38:22
Creation Checkpointed at scn: 0x0003.17539de7 02/13/2017 15:09:58
thread:1 rba:(0x1d6.48.10)
enabled threads: 01000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000
Offline scn: 0x0000.00000000 prev_range: 0
Online Checkpointed at scn: 0x0000.00000000
thread:0 rba:(0x0.0.0)
enabled threads: 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000
Hot Backup end marker scn: 0x0000.00000000
aux_file is NOT DEFINED
Plugged readony: NO
Plugin scnscn: 0x0000.00000000
Plugin resetlogs scn/timescn: 0x0000.00000000 01/01/1988 00:00:00
Foreign creation scn/timescn: 0x0000.00000000 01/01/1988 00:00:00
Foreign checkpoint scn/timescn: 0x0000.00000000 01/01/1988 00:00:00
Online move state: 0
V10 STYLE FILE HEADER:
Compatibility Vsn = 186647552=0xb200400
Db ID=1337401710=0x4fb7216e, Db Name='BOOK'
Activation ID=0=0x0
Control Seq=39840=0x9ba0, File size=5120=0x1400
File Number=6, Blksiz=8192, File Type=3 DATA
Tablespace #7 - TEA rel_fn:6
Creation at scn: 0x0003.17539de7 02/13/2017 15:09:58
Backup taken at scn: 0x0003.1768abb1 04/13/2018 15:39:15 thread:1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--//发出热备份模式的scn信息.
reset logs count:0x35711eb0 scn: 0x0000.000e2006
prev reset logs count:0x3121c97a scn: 0x0000.00000001
recovered at 04/13/2018 09:38:35
status:0x1 root dba:0x00000000 chkpt cnt: 318 ctl cnt:317
begin-hot-backup file size: 5120
Checkpointed at scn: 0x0003.1768abb1 04/13/2018 15:39:15
thread:1 rba:(0x2f7.a85b.10)
enabled threads: 01000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000
Backup Checkpointed at scn: 0x0003.1768abdf 04/13/2018 15:39:56
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--//备份过程中发出的检查点信息.
thread:1 rba:(0x2f7.a886.10)
enabled threads: 01000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000
External cache id: 0x0 0x0 0x0 0x0
Absolute fuzzy scn: 0x0000.00000000
Recovery fuzzy scn: 0x0000.00000000 01/01/1988 00:00:00
Terminal Recovery Stamp 01/01/1988 00:00:00
Platform Information: Creation Platform ID: 13
Current Platform ID: 13 Last Platform ID: 13
DUMP OF TEMP FILES: 1 files in database

5.继续测试,使用bbed修改看看:
--//使用bbed修改看看,减少kcvfh.kcvfhbcp.kcvcpscn-11看看.

SYS@book> shutdown abort ;
ORACLE instance shut down.

--//使用bbed修改:
BBED> p /d dba 6,1 kcvfh.kcvfhbcp.kcvcpscn
struct kcvcpscn, 8 bytes @152
ub4 kscnbas @152 392735711
ub2 kscnwrp @156 3

BBED> assign dba 6,1 kcvfh.kcvfhbcp.kcvcpscn.kscnbas=392735700
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y
ub4 kscnbas @152 0x1768abd4

BBED> sum apply dba 6,1
Check value for File 6, Block 1:
current = 0xcf4c, required = 0xcf4c

BBED> p dba 6,1 kcvfh.kcvfhbcp.kcvcpscn
struct kcvcpscn, 8 bytes @152
ub4 kscnbas @152 0x1768abd4
ub2 kscnwrp @156 0x0003

SYS@book> @ &r/16to10 31768abd4
16 to 10 DEC
------------
13277637588
--//减少到13277637588.

SYS@book> startup
ORACLE instance started.
Total System Global Area 634732544 bytes
Fixed Size 2255792 bytes
Variable Size 197133392 bytes
Database Buffers 427819008 bytes
Redo Buffers 7524352 bytes
Database mounted.
ORA-10873: file 6 needs to be either taken out of backup mode or media recovered
ORA-01110: data file 6: '/mnt/ramdisk/book/tea01.dbf'

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- -------------------------------------------------- ------------------------------
1 13277637599 2018-04-13 15:39:56 7 925702 ONLINE 941 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277637553 2018-04-13 15:39:15 13276257767 925702 ONLINE 318 YES /mnt/ramdisk/book/tea01.dbf TEA

SYS@book> alter tablespace tea end backup ;
Tablespace altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- -------------------------------------------------- ------------------------------
1 13277637599 2018-04-13 15:39:56 7 925702 ONLINE 941 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277637588 2018-04-13 15:39:56 13276257767 925702 ONLINE 319 YES /mnt/ramdisk/book/tea01.dbf TEA

--//与前面修改一致,也验证了自己的判断.

6.继续测试,是否在热备份模式可以offline表空间:

SYS@book> alter database open ;
Database altered.

SYS@book> alter tablespace tea begin backup ;
Tablespace altered.

SYS@book> SELECT file#, CHECKPOINT_CHANGE#, CHECKPOINT_TIME,CREATION_CHANGE# , RESETLOGS_CHANGE#,status, CHECKPOINT_COUNT,fuzzy,name,tablespace_name FROM v$datafile_header where file# in (1,6);
FILE# CHECKPOINT_CHANGE# CHECKPOINT_TIME CREATION_CHANGE# RESETLOGS_CHANGE# STATUS CHECKPOINT_COUNT FUZ NAME TABLESPACE_NAME
----- ------------------ ------------------- ---------------- ----------------- ------- ---------------- --- -------------------------------------------------- ------------------------------
1 13277658196 2018-04-13 15:56:09 7 925702 ONLINE 944 YES /mnt/ramdisk/book/system01.dbf SYSTEM
6 13277658833 2018-04-13 15:59:49 13276257767 925702 ONLINE 329 YES /mnt/ramdisk/book/tea01.dbf TEA

SYS@book> alter tablespace tea offline;
alter tablespace tea offline
*
ERROR at line 1:
ORA-01150: cannot prevent writes - file 6 has online backup set
ORA-01110: data file 6: '/mnt/ramdisk/book/tea01.dbf'

$ oerr ora 01150
01150, 00000, "cannot prevent writes - file %s has online backup set"
// *Cause: An attempt to make a tablespace read only or offline normal found
// that an online backup is still in progress. It will be necessary
// to write the file header to end the backup, but that would not
// be allowed if this command succeeded.
// *Action: End the backup of the offending tablespace and retry this command.

SYS@book> alter tablespace tea offline immediate ;
Tablespace altered.

--//强制ok.

SYS@book> alter tablespace tea online;
alter tablespace tea online
*
ERROR at line 1:
ORA-01113: file 6 needs media recovery
ORA-01110: data file 6: '/mnt/ramdisk/book/tea01.dbf'

SYS@book> select * from v$backup where file# in (1,6);
FILE# STATUS CHANGE# TIME
----- ------------------ ------------ -------------------
1 NOT ACTIVE 13277525910 2018-04-13 09:03:44
6 NOT ACTIVE 13277658833 2018-04-13 15:59:49

--//热备模式已经关闭.

--//总结:
--//虽然热备份已经不常用,也不推荐使用.还是佩服oracle设计时的考虑周全,在发出检查点时记录最新的scn号数据文件中即使在热备份模式下.
--//这样在恢复时减少使用归档的数量.




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