This document provides instructions and queries to check the status and health of a physical standby database. It includes steps to count archived logs, check synchronization levels between the primary and standby, view received and applied logs, monitor messages, identify issues with log transmission, check if managed recovery is enabled, and monitor and manage the recovery process.

1. Verify standby environment
Physical standby database
Count the existing archived logs n the standby database:
select count(*) from v$archived_log;
Then archive the current log on the primary database:
Alter system archive log current;
Then, count the archived logs on the standby database again. It should have been increased by
one.
Level of synchronization
To see if there is a problem with the archiving destinations (such as that destination that
transmits logs), query v$archive_dest_status.
Select archived_thread#, archived_seq#, applied_thread#,
applied_seq# from v$archive_dest_status;
Show received logs
On a physical standby database, the received archived redo logs can be displayed like this:
Select registrar, creator, thread#, sequence#, first_change#,
next_change# from v$archived_log;
Show applied archived redo log
select thread#, sequence#, first_change#, next_change# from
v$log_history;
Show messages
Use v$dataguard_status to display messages. Dest_id refers to what is configured with
log_archive_dest_n.
select message from v$dataguard_status where dest_id = 2;

2. The query was executed on the primary database, and it shows that the destination 2 cannot
deliver its logs.
ARCH: Error 12535 Creating archive log file to 'to_standby'
ARCH: Error 12535 Creating archive log file to 'to_standby'
ARCH: Error 12535 Creating archive log file to 'to_standby'
Broken network connections: If the network connection is broken, the standby database writes
RFS: Possible network disconnect with primary database. The primary database writes: Network
asynch I/O wait error 3114 log 3 service 'to_standby'.
Archived logs that are not transmitted
The following query assumes that the archives are locally stored on destination 1 and sent to the
remote server on destination 2.
select
substr(local.name,1,50) "Archive Name",
case when remote.sequence# is null then 'NOT TRANSMITTED'
else 'transmitted'
end,
local.sequence#,
local.thread#
from
(select * from v$archived_log where dest_id = 1) local
left join
(select * from v$archived_log where dest_id = 2) remote
on local.sequence# = remote.sequence# and
local.thread# = remote.thread#
order by local.sequence#;
Is standby database performing managed recovery
Select process, status from v$managed_standby;
If there is a MRP or a MRP0 process, the database is performing managed recovery.
Monitoring the recovery process
select process, status, thread#, sequence#, block#, blocks from
v$managed_standby;

3. alter database recover managed standby database disconnect from
session;
alter database recover managed standby database cancel;
alter system set log_archive_dest_state_2=defer;