Each log group contains at least one log member. To be safe, it is recommended that each log group contain more than two members, and each log member is located at a different location.diskWhen writing logs, Oracle will write the same content into multiple members of the same log group.
There are at least 2 log groups, with the same size in each group and at least 1 members.
View log file groups and members;
SYS@testdb> select group#,bytes/1024/1024 M,members from v$log;
Additional members in log group
SYS@testdb> alter database add logfile member ‘/u01/app/oracle/oradata/testdb/redo01_II.log’ to group 1;
See
SYS@testdb> select group#,member from v$logfile order by 1;
Delete log after logging.
SYS@testdb> alter system switch logfile;
Delete member
SYS@testdb> alter database drop logfile member ‘/u01/app/oracle/oradata/testdb/redo03_II.log’;
Add log group
> alter database add logfile group <Group number & gt; (& lt; member location and name & gt; & lt; member location and name & gt;) size & lt; member file size & gt;
> alter database add logfile group 4 (‘/u01/app/oracle/oradata/VDEDU/redo04_a.log’,’/u01/app/oracle/oradata/VDEDU/redo04_b.log’) size 50M;
View state
SYS@testdb> select group ,bytes/1024/1024 M,members,archived, status from v$log;
Changing day to group size
To change the file group size, create a new group that is different in size from the previous group, switch to use, and delete the previous group after the archive is finished.
> alter database add logfile group 11 (‘/u01/app/oracle/oradata/testdb/redo11_a.log’,’/u01/app/oracle/oradata/testdb/redo11_b.log’) size 100M;
> alter database add logfile group 12 (‘/u01/app/oracle/oradata/testdb/redo12_a.log’,’/u01/app/oracle/oradata/testdb/redo12_b.log’) size 100M;
> alter database add logfile group 13 (‘/u01/app/oracle/oradata/testdb/redo13_a.log’,’/u01/app/oracle/oradata/testdb/redo13_b.log’) size 100M;
SYS@testdb> select group#,bytes/1024/1024 M,members,archived,status from v$log;
SYS@testdb> alter system switch logfile;
SYS@testdb> alter database drop logfile group 1;
SYS@testdb> alter database drop logfile group 4;