将rac环境迁移单机后，删除redo的thread 2告警，告警信息如下

SQL> select thread#,status,enabled from v$thread;

   THREAD# STATUS ENABLED
---------- ------ --------
     1 OPEN   PUBLIC
     2 CLOSED PUBLIC

SQL> select group#,thread#,archived,status from v$log;

    GROUP#    THREAD# ARC STATUS
---------- ---------- --- ----------------
     1        1 YES INACTIVE
     2        1 NO  CURRENT
     3        2 YES UNUSED
     4        2 YES UNUSED

SQL> alter database drop logfile group 3
*
ERROR at line 1:
ORA-01623: log 3 is current log for instance orcl2 (thread 2) - cannot drop
ORA-00312: online log 3 thread 2: '/data/orcl/onlinelog/redo3.log'

SQL> alter database drop logfile group 4
*
ERROR at line 1:
ORA-01623: log 4 is current log for instance orcl2 (thread 2) - cannot drop
ORA-00312: online log 4 thread 2: '/data/orcl/onlinelog/redo4.log'

处理办法

SQL> alter database disable thread 2;
SQL> alter database drop logfile group 3;
SQL> alter database drop logfile group 4;