查看日志状态：select * from v$log;
日志路径：select * from v$logfile;
大小达到限制时，日志会自动切换到下一个组
日志状态：ACTIVE(recovery需要，脏数据未同步) CURRENT(实例恢复时所需要的) INACTIVE UNUSED
alter system checkpoint;//执行检查点之后，ACTIVE会变成INACTIVE
手动切换日志：alter system switch logfile;
查看日志切换频率：select to_char(FIRST_TIME,'yyyymmddhh24') FIRST_TIME,count(*) from v$log_history group by to_char(FIRST_TIME,'yyyymmddhh24') order by 1;
减少日志切换频率：添加新的日志文件
alter database add logfile '/home/oracle/redo04.log' size 100m;
alter database add logfile '/home/oracle/redo05.log' size 100m;
alter database add logfile '/home/oracle/redo06.log' size 100m;
切换当前组：alter system switch logfile;
删除原来的组：
alter database drop logfile group 1;--删除第一个组
c/1/2--删除第二个组
c/2/3--删除第三个组
组中添加成员(用于备份，防止文件损坏导致无法恢复)：
alter database add logfile member '/home/oracle/redo01.log' to group 1;--向第一组添加一个成员
alter database add logfile member '/home/oracle/redo04a.log' to group 2;--向第二组添加一个成员
alter database add logfile member '/home/oracle/redo05a.log' to group 3;--向第三组添加一个成员
组1的日志文件都删除时：lsof | grep /home/oracle/redo01.log
cd /proc/进程号/fd
cp 对应的文件号 /home/oracle/redo01.log.old
移动日志文件：
停止数据库：shut immediate
移动日志文件：
mv /home/oracle/redo01.log /u01/app/oracle/oradata/myorcl/
mv /home/oracle/redo04a.log /u01/app/oracle/oradata/myorcl/
mv /home/oracle/redo05a.log /u01/app/oracle/oradata/myorcl/
startup mount
修改参数：
alter database rename file '/home/oracle/redo01.log' to '/u01/app/oracle/oradata/myorcl/redo01.log';
alter database rename file '/home/oracle/redo04a.log' to '/u01/app/oracle/oradata/myorcl/redo04a.log';
alter database rename file '/home/oracle/redo05a.log' to '/u01/app/oracle/oradata/myorcl/redo05a.log';
查看当前数据库是否归档(sqlplus环境命令)：archive log list
归档：
正常停止数据库：shut immediate
启动到mount：startup mount
切换到归档模式：alter database archivelog;
打开数据库：alter database open;
archive log list
归档模式下：切换日志时会拷贝上一个日志文件到归档目录
创建归档目录：mkdir /home/oracle/arc_myorcl_dest1
修改归档目录：alter system set log_archive_dest_1='location=/home/oracle/arc_myorcl_dest1/';--log_archive_dest_n一共31个，1-10自己使用
查看归档信息：select sequence#,name from v$archived_log;
查看归档失败的信息：select error from v$archive_dest where dest_id=1;
手动归档(调用服务进程，正常是归档进程*arc*)：alter system archive log sequence 48 to '/home/oracle/arc_myorcl_dest1/';