在一个dg环境中，配置的是实时同步,需要增加主库的redo大小和组数,本来是一个很简单的问题,解决思路是：先备库增加standby redo删除老standby redo,然后主库增加redo删除老redo,备库增加新redo删除老redo,最后主库增加standby redo。但是在实施过程中，遇到了一些细节性的问题，主要是学习到了log_file_name_convert如果不配置,将导致备库redo 文件不能被删除
standby redo log管理
增加standby redo log
SQL> alter database add standby logfile group 8 ('/data/oradata/wasudb/st_redo08.log') size 200M;
alter database add standby logfile group 8 ('/data/oradata/wasudb/st_redo08.log') size 200M
*
ERROR at line 1:
ORA-01156: recovery in progress may need access to files
SQL> alter database recover managed standby database cancel;
Database altered.
SQL> alter database add standby logfile group 9 ('/data/oradata/wasudb/st_redo09.log') size 200M;
Database altered.
SQL> alter database add standby logfile group 10 ('/data/oradata/wasudb/st_redo10.log') size 200M;
Database altered.
SQL> alter database add standby logfile group 11 ('/data/oradata/wasudb/st_redo11.log') size 200M;
Database altered.
SQL> alter database add standby logfile group 12 ('/data/oradata/wasudb/st_redo12.log') size 200M;
Database altered.
删除standby redo log
SQL> alter database drop logfile group 4;
alter database drop logfile group 4
*
ERROR at line 1:
ORA-00261: log 4 of thread 1 is being archived or modified
ORA-00312: online log 4 thread 1: '/data/oradata/wasudb/st_redo04.log'
SQL> alter database drop logfile group 5;;
Database altered.
SQL> alter database drop logfile group 6;
Database altered.
SQL> alter database drop logfile group 7;
Database altered.
--在主库多次执行switch logfile
SQL> alter database drop logfile group 4;
Database altered.
主库redo log 管理
增加redo log
SQL> alter database add logfile group 21 ('/data/oradata/wasudb/redo21.log') size 200m;
Database altered.
SQL> alter database add logfile group 22 ('/data/oradata/wasudb/redo22.log') size 200m;
Database altered.
SQL> alter database add logfile group 23 ('/data/oradata/wasudb/redo23.log') size 200m;
Database altered.
SQL> alter database add logfile group 24 ('/data/oradata/wasudb/redo24.log') size 200m;
Database altered.
删除redo log
SQL> alter database drop logfile group 1;
Database altered.
SQL> alter database drop logfile group 2;
Database altered.
SQL> alter database drop logfile group 3;
Database altered.
--这里涉及到多次switch logfile,需要确定redo是inactive才能够删除
备库redo log管理
增加redo log
SQL> alter database add logfile group 21 ('/data/oradata/wasudb/redo21.log') size 200m;
alter database add logfile group 21 ('/data/oradata/wasudb/redo21.log') size 200m
*
ERROR at line 1:
ORA-01275: Operation ADD LOGFILE is not allowed if standby file management is automatic.
SQL> alter system set standby_file_management=manual;
System altered.
SQL> alter database add logfile group 21 ('/data/oradata/wasudb/redo21.log') size 200m;
Database altered.
SQL> alter database add logfile group 22 ('/data/oradata/wasudb/redo22.log') size 200m;
Database altered.
SQL> alter database add logfile group 23 ('/data/oradata/wasudb/redo23.log') size 200m;
Database altered.
SQL> alter database add logfile group 24 ('/data/oradata/wasudb/redo24.log') size 200m;
Database altered.
删除redo log
SQL> alter database drop logfile group 1;
alter database drop logfile group 1
*
ERROR at line 1:
ORA-01624: log 1 needed for crash recovery of instance wasudb (thread 1)
ORA-00312: online log 1 thread 1: '/data/oradata/wasudb/redo01.log'
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 1;
ALTER DATABASE CLEAR LOGFILE GROUP 1
*
ERROR at line 1:
ORA-19527: physical standby redo log must be renamed
ORA-00312: online log 1 thread 1: '/data/oradata/wasudb/redo01.log'
SQL> show parameter NAME_CONVERT
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_file_name_convert string
log_file_name_convert string
SQL> alter system set log_file_name_convert='/data/oradata/wasudb','/data/oradata/wasudb' scope=spfile;
System altered.
SQL> alter system set db_file_name_convert='/data/oradata/wasudb','/data/oradata/wasudb' scope=spfile;
System altered.
--重启数据库
SQL> show parameter file_name_convert;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_file_name_convert string /data/oradata/wasudb, /data/or
adata/wasudb
log_file_name_convert string /data/oradata/wasudb, /data/or
adata/wasudb
SQL> alter database drop logfile group 1;
alter database drop logfile group 1
*
ERROR at line 1:
ORA-01624: log 1 needed for crash recovery of instance wasudb (thread 1)
ORA-00312: online log 1 thread 1: '/data/oradata/wasudb/redo01.log'
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 1;
Database altered.
SQL> alter database drop logfile group 1;
Database altered.
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 2;
Database altered.
SQL> alter database drop logfile group 2;
Database altered.
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 3;
Database altered.
SQL> alter database drop logfile group 3;
Database altered.
主库standby redo log管理
增加standby redo
SQL> alter database add logfile group 21 ('/data/oradata/wasudb/redo21.log') size 200m;
Database altered.
SQL> alter database add logfile group 22 ('/data/oradata/wasudb/redo22.log') size 200m;
Database altered.
SQL> alter database add logfile group 23 ('/data/oradata/wasudb/redo23.log') size 200m;
Database altered.
SQL> alter database add logfile group 24 ('/data/oradata/wasudb/redo24.log') size 200m;
Database altered.
删除standby redo
SQL> alter database drop logfile group 4;
Database altered.
SQL> alter database drop logfile group 5;
Database altered.
SQL> alter database drop logfile group 6;
Database altered.
SQL> alter database drop logfile group 7;
Database altered.
后续工作
SQL> alter system set standby_file_management=auto;
System altered.
SQL> alter database recover managed standby database using current logfile disconnect from session;
Database altered.
至此修改dataguard环境中的redo大小和增加redo组数的操作基本完成.在这里主要修正了自己以前对log_file_name_convert的认识，我以前以为如果我的主备库redo对应的目录一致不用配置该参数,今天通过查询MOS发现从10.2开始数据库为了能实现dg的快速切换在mrp启动的时候会去尝试清理备库redo,如果备库没有redo,或者log_file_name_convert配置不正确导致不能正常执行这个清理工作,数据库就会报ORA-19527,特别是在mrp进程启动之时.对于本次出现执行CLEAR LOGFILE命令也出现该问题,确实有点过犹不及了.这里也就是提醒我们:就算redo file,datafile主备位置相同,也建议配置log_file_name_convert和db_file_name_convert参数,提高dg健壮性.
