Adding large size redo logs for import

set target db in archivelog mode

srvctl stop database -d db_name -o immediate
startup mount
alter database archivelog;
shut immediate;
srvctl start database -d db_name

check current redo logfile size and member

select group#,thread#,status, bytes/1024/1024 "size in MB" from v$log;
select group#, member  from v$logfile order by 1;

ensure that diskgroup /FS has enough space to accomodate large redologs other wise use DG with enough space. i used FRA

alter database add logfile thread 1
group 5 ('+REDO','+DATA_FC') size 500M,
group 6 ('+REDO','+DATA_FC') size 500M;

alter database add logfile thread 2
group 7 ('+REDO','+DATA_FC') size  500M,
group 8 ('+REDO','+DATA_FC') size  500M;


alter database add logfile thread 1
group 9 ('+REDO','+DATA_FC') size 500M,
group 10 ('+REDO','+DATA_FC') size 500M;


alter database add logfile thread 2
group 11 ('+REDO','+DATA_FC') size  500M,
group 12 ('+REDO','+DATA_FC') size  500M;

alter database add logfile thread 1
group 13 ('+REDO','+DATA_FC') size 500M,
group 14 ('+REDO','+DATA_FC') size 500M;


alter database add logfile thread 2
group 15 ('+REDO','+DATA_FC') size  500M,
group 16 ('+REDO','+DATA_FC') size  500M;

drop old redo log groups

alter system archive log current;
alter system checkpoint;
alter database drop logfile group 1;
alter database drop logfile group 2;
alter database drop logfile group 3;
alter database drop logfile group 4;

verify the new reod log groups

select group#,thread#,status, bytes/1024/1024 "size in MB" from v$log;
select group#, member  from v$logfile order by 1;