[20180423]flashback tablespace与snapshot standby.txt
[20180423]flashback tablespace与snapshot standby.txt
--//缺省建立表空间是打开flashback on,如果某个表空间flashback off,在dg启动snapshot standby时注意,可能"回不来",
--//通过测试说明问题.
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.设置备库tea表空间关闭flashback.
SCOTT@book> alter tablespace tea flashback off;
Tablespace altered.
SCOTT@book> select * from v$tablespace;
TS# NAME INC BIG FLA ENC
------------ --------- --- --- --- ---
0 SYSTEM YES NO YES
1 SYSAUX YES NO YES
2 UNDOTBS1 YES NO YES
4 USERS YES NO YES
3 TEMP NO NO YES
6 EXAMPLE YES NO YES
7 TEA YES NO NO
7 rows selected.
--//tea表空间FLASHBACK_ON设置为NO.注意这些信息应该记录在控制文件,你可以发现备库还是On .
--//备库:
SYS@bookdg> select flashback_on from v$database;
FLASHBACK_ON
------------------
NO
SYS@bookdg> select * from v$tablespace;
TS# NAME INC BIG FLA ENC
---------- -------------------- --- --- --- ---
0 SYSTEM YES NO YES
1 SYSAUX YES NO YES
2 UNDOTBS1 YES NO YES
4 USERS YES NO YES
3 TEMP NO NO YES
6 EXAMPLE YES NO YES
7 TEA YES NO YES
7 rows selected.
--//备库还是yes,tea表空间.
SYS@bookdg> alter tablespace tea flashback off;
alter tablespace tea flashback off
*
ERROR at line 1:
ORA-16000: database open for read-only access
--//无法在open read only修改.
SYS@bookdg> startup mount
ORACLE instance started.
Total System Global Area 634732544 bytes
Fixed Size 2255792 bytes
Variable Size 197133392 bytes
Database Buffers 427819008 bytes
Redo Buffers 7524352 bytes
Database mounted.
SYS@bookdg> alter tablespace tea flashback off;
Tablespace altered.
SYS@bookdg> select * from v$tablespace;
TS# NAME INC BIG FLA ENC
---------- -------------------- --- --- --- ---
0 SYSTEM YES NO YES
1 SYSAUX YES NO YES
2 UNDOTBS1 YES NO YES
4 USERS YES NO YES
3 TEMP NO NO YES
6 EXAMPLE YES NO YES
7 TEA YES NO NO
7 rows selected.
--//OK,现在成功.
3.备库打开snapshot standby:
--//参考http://blog.itpub.net/267265/viewspace-2134547/
--//实际上就是保证存储点,只要闪回区足够,许多dml操作没有问题,在转换physical standby时,返回原来的存储点;
--//备库:
SYS@bookdg> alter database convert to snapshot standby;
Database altered.
SYS@bookdg> select database_role from v$database;
DATABASE_ROLE
----------------
SNAPSHOT STANDBY
SYS@bookdg> alter database open ;
Database altered.
SCOTT@bookdg> create table tt1 tablespace tea as select * from dba_objects;
Table created.
--//在主库也产生一些日志对于tea表空间:
SCOTT@book> create table empx tablespace tea as select * from emp;
Table created.
--//现在转换为physical standby
--//备库:
SYS@bookdg> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SYS@bookdg> startup mount
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.
SYS@bookdg> alter database convert to physical standby ;
alter database convert to physical standby
*
ERROR at line 1:
ORA-38753: Cannot flashback data file 6; no flashback log data.
ORA-01110: data file 6: '/mnt/ramdisk/book/tea01.dbf'
--//可以发现备库的数据文件6无法转换,这个应该引起足够重视,在备库转换为snapshot standby时,注意检查表空间是否flashvback是否都是on的状态.
$ oerr ora 38753
38753, 00000, "Cannot flashback data file %s; no flashback log data."
// *Cause: An attempt to perform a FLASHBACK DATABASE failed because the file
// does not have enough flashback log data to cover the time to
// flash back. Either the file did not have flashback generation
// enabled for it, or had flashback generation turned off for it
// some time during the time span of the flashback.
// *Action: The file cannot be flashed back. The file must be taken offline
// or the tablespace dropped before continuing with the FLASHBACK
// DATABASE command.
4.恢复:
--//简单一点,主库tea表空间设置为read only;
--//主库:
SCOTT@book> alter tablespace tea read only;
Tablespace altered.
$ scp /mnt/ramdisk/book/tea01.dbf oracle@192.168.100.40:/mnt/ramdisk/book/
tea01.dbf 100% 40MB 40.0MB/s 00:01
--//备库:
SYS@bookdg> alter database convert to physical standby ;
alter database convert to physical standby
*
ERROR at line 1:
ORA-38753: Cannot flashback data file 6; no flashback log data.
ORA-01110: data file 6: '/mnt/ramdisk/book/tea01.dbf'
--//不行:
SYS@bookdg> alter tablespace tea flashback on;
Tablespace altered.
SYS@bookdg> alter database convert to physical standby ;
alter database convert to physical standby
*
ERROR at line 1:
ORA-19926: Database cannot be converted at this time
--//根本不能这样转换.
SYS@bookdg> alter tablespace tea offline;
alter tablespace tea offline
*
ERROR at line 1:
ORA-01109: database not open
SYS@bookdg> alter database datafile 6 offline;
Database altered.
--//关闭备库重来.
SYS@bookdg> startup mount
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.
SYS@bookdg> alter database convert to physical standby ;
Database altered.
SYS@bookdg> shutdown immediate
ORA-01507: database not mounted
ORACLE instance shut down.
SYS@bookdg> startup mount
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.
SYS@bookdg> alter database datafile 6 online;
Database altered.
SYS@bookdg> alter database recover managed standby database using current logfile disconnect ;
Database altered.
SYS@bookdg> @ &r/dg/dg
PROCESS PID STATUS CLIENT_P GROUP# THREAD# SEQUENCE# BLOCK# BLOCKS DELAY_MINS
--------- ------- ------------ -------- ------ ------- ---------- ---------- ---------- ----------
ARCH 2394 CONNECTED ARCH N/A 0 0 0 0 0
ARCH 2396 CONNECTED ARCH N/A 0 0 0 0 0
ARCH 2398 CONNECTED ARCH N/A 0 0 0 0 0
RFS 2403 IDLE UNKNOWN N/A 0 0 0 0 0
RFS 2405 IDLE LGWR 2 1 789 50 1 0
ARCH 2400 CLOSING ARCH 4 1 788 1 183 0
MRP0 2407 APPLYING_LOG N/A N/A 1 789 50 102400 0
7 rows selected.
--//日志开始传输并应用.
SYS@bookdg> alter database recover managed standby database cancel ;
Database altered.
SYS@bookdg> alter database open read only;
Database altered.
SYS@bookdg> alter database recover managed standby database using current logfile disconnect ;
Database altered.
SYS@bookdg> select count(*) from scott.empx;
COUNT(*)
----------
14
SYS@bookdg> select count(*) from scott.tt1;
select count(*) from scott.tt1
*
ERROR at line 1:
ORA-00942: table or view does not exist
--//测试时建立的表不存在.
--//主库执行:
SCOTT@book> alter tablespace tea read write;
Tablespace altered.
SCOTT@book> delete from empx where rownum=1;
1 row deleted.
SCOTT@book> commit ;
Commit complete.
--//在备库检查,发现少一条记录.
SYS@bookdg> select count(*) from scott.empx;
COUNT(*)
----------
13
总结:
--//这个在以后工作中注意,在转换snapshot standby,注意表空间flaashback是否在on状态.
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