Describe 襴襦蠏誤殊伎 here
SQL> -- 襴襦蠏 殊 伎 
SQL> set linesize 150 pagesize 999
SQL> connect internal
郁屋給.
SQL> select * from v$log;

    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TI
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------
         1          1        658    1048576          1 NO  INACTIVE                472248 03/10/30
         2          1        659    1048576          1 NO  CURRENT                 472305 03/10/30
         3          1        657    1048576          1 NO  INACTIVE                452040 03/10/24

SQL> select 1024*1024 from dual;

 1024*1024
----------
   1048576

SQL> -- 1MB ″  蟆 覲伎碁.... 蟆 ′ ..
SQL> select * from tab
  2  where tname like '%FILE%';

TNAME                          TABTYPE  CLUSTERID
------------------------------ ------- ----------
C_FILE#_BLOCK#                 CLUSTER
DBA_DATA_FILES                 VIEW
DBA_EXP_FILES                  VIEW
DBA_PROFILES                   VIEW
DBA_TEMP_FILES                 VIEW
FILE$                          TABLE
FILEXT$                        VIEW
GV_$BACKUP_DATAFILE            VIEW
GV_$CONTROLFILE                VIEW
GV_$CONTROLFILE_RECORD_SECTION VIEW
GV_$DATAFILE                   VIEW
GV_$DATAFILE_COPY              VIEW
GV_$DATAFILE_HEADER            VIEW
GV_$DBFILE                     VIEW
GV_$FILESTAT                   VIEW
GV_$FILE_PING                  VIEW
GV_$LOGFILE                    VIEW
GV_$PROXY_DATAFILE             VIEW
GV_$PWFILE_USERS               VIEW
GV_$RECOVERY_FILE_STATUS       VIEW
GV_$RECOVER_FILE               VIEW
GV_$TEMPFILE                   VIEW
LOADER_FILE_TS                 VIEW
PROFILE$                       TABLE
SYSFILES                       VIEW
V_$BACKUP_DATAFILE             VIEW
V_$CONTROLFILE                 VIEW
V_$CONTROLFILE_RECORD_SECTION  VIEW
V_$DATAFILE                    VIEW
V_$DATAFILE_COPY               VIEW
V_$DATAFILE_HEADER             VIEW
V_$DBFILE                      VIEW
V_$FILESTAT                    VIEW
V_$FILE_PING                   VIEW
V_$LOGFILE                     VIEW
V_$PROXY_DATAFILE              VIEW
V_$PWFILE_USERS                VIEW
V_$RECOVERY_FILE_STATUS        VIEW
V_$RECOVER_FILE                VIEW
V_$TEMPFILE                    VIEW

40 螳  給.

SQL> select * from v$logfile;

    GROUP# STATUS  MEMBER
---------- ------- -----------------------------------
         1 STALE   E:\ORACLE\ORADATA\ORA816\REDO03.LOG
         3 STALE   E:\ORACLE\ORADATA\ORA816\REDO01.LOG
         2         E:\ORACLE\ORADATA\ORA816\REDO02.LOG
SQL> -- 蠍一 螳 ろ 讌襷 れ襦 覿磯伎 . 
SQL> --   襦蠏 殊 覃伎 螻 り 覲企 螻, 蠏碁９朱 り
SQL> -- 螳伎 . 
SQL> -- 襦蠏  蠏碁９ 豢螳
SQL> alter database add logfile group 4
  2  ('E:\ORACLE\ORADATA\ORA816\REDO04.LOG') size 1M;

一危覯伎り 覲蟆暑給.

SQL> -- れ螻 螳 螳襯 襷企蟾讌 螳 豢螳  . 
SQL> alter database add logfile group 5
  2  ('E:\ORACLE\ORADATA\ORA816\REDO05.LOG',
  3   'E:\ORACLE\ORADATA\ORA816\REDO05_2.LOG') size 1M;

一危覯伎り 覲蟆暑給.

SQL> --襷企襷 豢螳
SQL> --襷企 size れ . 覃 襷企朱Μ  蠍郁 螳 伎螳   蠍 覓語企.
SQL> alter database add logfile member 'E:\ORACLE\ORADATA\ORA816\REDO01_2.LOG'
  2  to group 1;

一危覯伎り 覲蟆暑給.

SQL> alter database add logfile member 'E:\ORACLE\ORADATA\ORA816\REDO02_2.LOG'
  2  to group 2;

一危覯伎り 覲蟆暑給.

SQL> alter database add logfile member 'E:\ORACLE\ORADATA\ORA816\REDO03_2.LOG'
  2  to group 3;

一危覯伎り 覲蟆暑給.

SQL> alter database add logfile member 'E:\ORACLE\ORADATA\ORA816\REDO04_2.LOG'
  2  to group 4;

一危覯伎り 覲蟆暑給.

SQL> select * from v$log;

    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TI
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------
         1          1        658    1048576          2 NO  INACTIVE                472248 03/10/30
         2          1        659    1048576          2 NO  CURRENT                 472305 03/10/30
         3          1        657    1048576          2 NO  INACTIVE                452040 03/10/24
         4          1          0    1048576          2 YES UNUSED                       0
         5          1          0    1048576          2 YES UNUSED                       0

SQL> col group# format 999
SQL> col status format a20
SQL> col member format a50
SQL> select * from v$logfile;

GROUP# STATUS               MEMBER
------ -------------------- --------------------------------------------------
     1 STALE                E:\ORACLE\ORADATA\ORA816\REDO03.LOG
     3 STALE                E:\ORACLE\ORADATA\ORA816\REDO01.LOG
     2                      E:\ORACLE\ORADATA\ORA816\REDO02.LOG
     4                      E:\ORACLE\ORADATA\ORA816\REDO04.LOG
     5                      E:\ORACLE\ORADATA\ORA816\REDO05.LOG
     5                      E:\ORACLE\ORADATA\ORA816\REDO05_2.LOG
     1 INVALID              E:\ORACLE\ORADATA\ORA816\REDO01_2.LOG
     2 INVALID              E:\ORACLE\ORADATA\ORA816\REDO02_2.LOG
     3 INVALID              E:\ORACLE\ORADATA\ORA816\REDO03_2.LOG
     4 INVALID              E:\ORACLE\ORADATA\ORA816\REDO04_2.LOG

10 螳  給.

SQL> 

襴襦蠏 殊 襦 るジ ろ 覿 る 蟆 譯 譴. 覃 襦 LGWR螳
郁鍵 覓語 蟆渚 譴企 蟆 譴螻, 襦蠏 郁鍵朱 DBMS  殊 觜れ 
レ 豕   蠍 覓語企. 

襴襦蠏 殊 伎 焔伎  譯朱 讌襷  れ旧   襦蠏碁ゼ 郁鍵
伎 LGWR 襦語る  伎 狩伎  蟆企. 讀, CPU螳  螻  蟆企朱 襴.