Adding additional redo log groups online .

Oracle Database having Archive log enabled may face this error :  Can not allocate log, archival required .

One possible reason for this error is during the scenario of rapid generation of archive logs which indeed results in very frequent switching of redo logs. Number of redo log groups allocated may not be sufficient to handle to archive log switching.
 Hence we need to add additional redo log groups to avoid this error. we can add redo logs online .

Considering adding additional groups for 2 Node RAC Database, each instance already having 3 groups :

SQL> select group#, sequence#, bytes, members, status from v$log;

SQL> alter system switch logfile;

SQL> alter system checkpoint;

SQL> alter database backup controlfile to trace;

SQL> alter database add logfile thread 1 group 7 ( '<LOC>/oraDB_NAME_redo_001_1000Mp5','<LOC>/oraDB_NAME_redomirr_001_1000Mp5' ) size 1000M;

SQL> alter database add logfile thread 1 group 8 ( '<LOC>/oraDB_NAME_redo_001_1000Mp6','<LOC>/oraDB_NAME_redomirr_001_1000Mp6' ) size 1000M;

SQL> alter database add logfile thread 1 group 9 ( '<LOC>/oraDB_NAME_redo_001_1000Mp7','<LOC>/oraDB_NAME_redomirr_001_1000Mp7' ) size 1000M;

SQL> alter database add logfile thread 1 group 10 ( '<LOC>/oraDB_NAME_redo_001_1000Mp8','<LOC>/oraDB_NAME_redomirr_001_1000Mp8' ) size 1000M;

SQL> alter database add logfile thread 2 group 11 ( '<LOC>/oraDB_NAME_redo_001_1000Mp5','<LOC>/oraDB_NAME_redomirr_001_1000Mp5' ) size 1000M;

SQL> alter database add logfile thread 2 group 12 ( '<LOC>/oraDB_NAME_redo_001_1000Mp6','<LOC>/oraDB_NAME_redomirr_001_1000Mp6' ) size 1000M;

SQL> alter database add logfile thread 2 group 13 ( '<LOC>/oraDB_NAME_redo_001_1000Mp7','<LOC>/oraDB_NAME_redomirr_001_1000Mp7' ) size 1000M;

SQL> alter database add logfile thread 2 group 14 ( '<LOC>/oraDB_NAME_redo_001_1000Mp8','<LOC>/oraDB_NAME_redomirr_001_1000Mp8' ) size 1000M;

SQL> select group#, sequence#, bytes, members, status from v$log;

SQL> alter system switch logfile;

SQL> alter system checkpoint;

SQL> alter database backup controlfile to trace;

Cheers !!!!!!