Standby database is not applying redo logs due to missing archive log

Question

We use 9.2.0.7 Oracle Database. My goal is to create a physical standby database.
I have followed all the steps necessary to fulfill this in Oracle Data Guard Concepts and Administration manual. Archived redo logs are transmitted from primary to standby database regularly. But the logs are not applied due to archive log gap.
SQL> select process, status from v$managed_standby;
PROCESS STATUS
ARCH CONNECTED
ARCH CONNECTED
MRP0 WAIT_FOR_GAP
RFS RECEIVING
RFS ATTACHED
SQL> select * from v$archive_gap;
THREAD# LOW_SEQUENCE# HIGH_SEQUENCE#
1 503 677
I have tried to find the missing archives on the primary database, but was unable to. They have been deleted (somehow) regularly by the existing backup policy on the primary database. I have looked up the backups, but these archive logs are too old to be in the backup. Backup retention policy is 1 redundant backup of each file. I didn't save older backups as I didn't really need them from up to this point.
I have cross checked (using rman crosscheck) the archive log copies on the primary database and deleted the "obsolete" copies of archive logs. But, v$archived_log view on the primary database only marked those entries as "deleted". Unfortunately, the standby database is still waiting for those logs to "close the gap" and doesn't apply the redo logs at all. I am reluctant to recreate the control file on the primary database as I'm afraid this occurred through the regular database backup operations, due to current backup retention policy and it probably might happen again.
The standby creation procedure was done by using the data files from 3 days ago. The archive logs which are "producing the gap" are older than a month, and are probably unneeded for standby recovery.
What shall I do?
Kind regards and thanks in advance,
Milivoj

Answer 1

On a physical standby database
To determine if there is an archive gap on your physical standby database, query the V$ARCHIVE_GAP view as shown in the following example:
SQL> SELECT * FROM V$ARCHIVE_GAP;
THREAD# LOW_SEQUENCE# HIGH_SEQUENCE#
1 7 10
The output from the previous example indicates your physical standby database is currently missing log files from sequence 7 to sequence 10 for thread 1.
After you identify the gap, issue the following SQL statement on the primary database to locate the archived redo log files on your primary
database (assuming the local archive destination on the primary database is LOG_ARCHIVE_DEST_1):
SQL> SELECT NAME FROM V$ARCHIVED_LOG WHERE THREAD#=1 AND DEST_ID=1 AND 2> SEQUENCE# BETWEEN 7 AND 10;
NAME
/primary/thread1_dest/arcr_1_7.arc /primary/thread1_dest/arcr_1_8.arc /primary/thread1_dest/arcr_1_9.arc
Copy these log files to your physical standby database and register them using the ALTER DATABASE REGISTER LOGFILE statement on your physical standby database. For example:
SQL> ALTER DATABASE REGISTER LOGFILE
'/physical_standby1/thread1_dest/arcr_1_7.arc';
SQL> ALTER DATABASE REGISTER LOGFILE
'/physical_standby1/thread1_dest/arcr_1_8.arc';
After you register these log files on the physical standby database, you can restart Redo Apply.
Note:
The V$ARCHIVE_GAP fixed view on a physical standby database only returns the next gap that is currently blocking Redo Apply from continuing. After resolving the gap and starting Redo Apply, query the V$ARCHIVE_GAP fixed view again on the physical standby database to determine the next gap sequence, if there is one. Repeat this process until there are no more gaps.
Restoring the archived logs from the backup set
If the archived logs are not available in the archive destination then at that time we need to restore the required archived logs from the backup step. This task is accomplished in the following way.
To restore range specified archived logs:
Run {
Set archivelog destination to '/oracle/arch/arch_restore'
Restore archivelog from logseq=<xxxxx> until logseq=<xxxxxxx>
To restore all the archived logs:
Run {
Set archivelog destination to '/oracle/arch/arch_restore';
Restore archivelog all;
}