Perda de todos os Redo Logs – erro ao executar CLEAR

Eu fui testar hoje a recuperação da perda de todos os Redo Logs com CLEAR – incluindo o CLEAR UNARCHIVED para os Redo Logs ACTIVE (talvez) e CURRENT (certamente não foi arquivado), conforme comentário de alguém na postagem Vídeos de RMAN – em 12cR2, mas a instância caiu imediatamente, antes da execução de qualquer comando.

Eu utilizo esta recuperação no Treinamento DBA Júnior II, nesta mesma versão e também em Arquitetura CDB, e sempre funciona, mas desta vez não deu certo – o processo LG01, um Slave do Log Writer, caiu. Foi necessário realmente executar RESTORE e RECOVER.

06:42:22 SYS@ORCL> SELECT * FROM V$LOG;

    GROUP#    THREAD#  SEQUENCE#      BYTES  BLOCKSIZE    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME     CON_ID
---------- ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- ------------ --------- ----------
         4          1       4624  104857600        512          1 NO  CURRENT               13095792 20-JUN-17   1.8447E+19                    0
         5          1       4622  104857600        512          1 YES INACTIVE              13095641 20-JUN-17     13095646 20-JUN-17          0
         6          1       4623  104857600        512          1 YES ACTIVE                13095646 20-JUN-17     13095792 20-JUN-17          0

Elapsed: 00:00:00.02
06:42:24 SYS@ORCL> SELECT MEMBER FROM V$LOGFILE;

MEMBER
--------------------------------------------------
/u01/RedoLogs/RedoLog04.rdo
/u01/RedoLogs/RedoLog05.rdo
/u01/RedoLogs/RedoLog06.rdo

Elapsed: 00:00:00.01
06:42:28 SYS@ORCL> !rm /u01/RedoLogs/*

06:42:37 SYS@ORCL> ALTER DATABASE CLEAR LOGFILE GROUP 4;
ALTER DATABASE CLEAR LOGFILE GROUP 4
*
ERROR at line 1:
ORA-03135: connection lost contact
Process ID: 28862
Session ID: 286 Serial number: 26647


Elapsed: 00:00:00.03
06:43:43 SYS@ORCL> EXIT
Disconnected from Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production
[oracle@nerv10 ~]$ tail -1000 /u01/app/diag/rdbms/orcl/ORCL/trace/alert_ORCL.log
...
2017-06-20T06:43:21.876127-03:00
Errors in file /u01/app/diag/rdbms/orcl/ORCL/trace/ORCL_lg01_29201.trc:
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
2017-06-20T06:43:21.944083-03:00
Errors in file /u01/app/diag/rdbms/orcl/ORCL/trace/ORCL_lg01_29201.trc:
ORA-00313: open failed for members of log group 4 of thread 1
2017-06-20T06:43:22.023077-03:00
Instance Critical Process (pid: 24, ospid: 29201, LG01) died unexpectedly
PMON (ospid: 29152): terminating the instance due to error 12752
2017-06-20T06:43:22.360586-03:00
System state dump requested by (instance=1, osid=29152 (PMON)), summary=[abnormal instance termination].
System State dumped to trace file /u01/app/diag/rdbms/orcl/ORCL/trace/ORCL_diag_29175_20170620064322.trc
...