Diagnosis Oracle Physical Standby Data Guard Configuration

-- NAME: DG_Physical_Standby_Diagnosis.sql
-- ------------------------------------------------------------------------
-- AUTHOR: Mohammad Abdul Momin Arju
-- September 2010.
-- ------------------------------------------------------------------------
-- PURPOSE:
-- This script is used to troubleshoot Oracle Data Guard issues for
-- physical standby database.
-- ------------------------------------------------------------------------
-- DISCLAIMER:
-- This script is provided for educational purposes only.
-- Test it before you run in your production database.
-- ------------------------------------------------------------------------
-- Content of the Script

set echo off 
set feedback off 
column timecol new_value timestamp 
column spool_extension new_value suffix 
select to_char(sysdate,'Mondd_hhmi') timecol, 
'.out' spool_extension from sys.dual; 
column output new_value dbname 
select value || '_' output 
from v$parameter where name = 'db_name'; 
spool dgdiag_phystby_&&dbname&×tamp&&suffix 
set lines 200 
set pagesize 35 
set trim on 
set trims on 
alter session set nls_date_format = 'MON-DD-YYYY HH24:MI:SS'; 
set feedback on 
select to_char(sysdate) time from dual; 

set echo on 

-- ARCHIVER can be STOPPED/STARTED/FAILED -
-- Archiver FAILED means archiver failed to archive a log last time but will try
-- again within 5 minutes
-- LOG_SWITCH_WAIT can be ARCHIVE LOG/CLEAR LOG/CHECKPOINT/NULL -
-- NULL means ALTER SYSTEM SWITCH LOGFILE is hung but there is room in the current online redo log

column host_name format a20 tru 
column version format a9 tru 
select instance_name,host_name,version,archiver,log_switch_wait from v$instance; 

-- Select from v$database will give us the generic information about how this standby is
-- setup. The database_role can be SNAPSHOT STANDBY/LOGICAL STANDBY/PHYSICAL STANDBY/PRIMARY
-- It should be standby for standby database. PROTECTION_MODE can be,
-- MAXIMUM PROTECTION - Database is running in maximized protection mode
-- MAXIMUM AVAILABILITY - Database is running in maximized availability mode
-- RESYNCHRONIZATION - Database is running in resynchronization mode
-- MAXIMUM PERFORMANCE - Database is running in maximized protection mode
-- UNPROTECTED - Database is unprotected (this normally occurs when the primary database is mounted and not open)

-- If protection_level is different than protection_mode then for some
-- reason the mode listed in protection_mode experienced a need to downgrade. Once the
-- error condition has been corrected the protection_level should match the protection_mode
-- after the next log switch.

column ROLE format a7 tru 
select name,database_role,log_mode,controlfile_type,protection_mode,protection_level  
from v$database; 

-- Force logging is not mandatory but is recommended. Supplemental logging should be enabled
-- on the standby if a logical standby is in the configuration. During normal
-- operations it is acceptable for SWITCHOVER_STATUS to be SESSIONS ACTIVE or NOT ALLOWED.

column force_logging format a13 tru 
column remote_archive format a14 tru 
column dataguard_broker format a16 tru 
select force_logging,remote_archive,supplemental_log_data_pk,supplemental_log_data_ui, 
switchover_status,dataguard_broker from v$database;  

-- This query produces a list of all archive destinations and shows if they are enabled,
-- what process is servicing that destination, if the destination is local or remote,
-- and if remote what the current mount ID is.
-- Status can be, VALID - Initialized and available
-- INACTIVE - No destination information
-- DEFERRED - Manually disabled by the user
-- ERROR - Error during open or copy
-- DISABLED - Disabled after error
-- BAD PARAM - Parameter has errors
-- ALTERNATE - Destination is in an alternate state
-- FULL - Exceeded quota size for the destination.
-- For a physical standby we should have at least one remote destination that points the primary set.

COLUMN destination FORMAT A35 WRAP 
column process format a10 
column archiver format a10 
column ID format 99 

select dest_id "ID",destination,status,target, 
archiver,schedule,process,mountid  
from v$archive_dest; 

-- If the protection mode of the standby is set to anything higher than max performance
-- then we need to make sure the remote destination that points to the primary is set
-- with the correct options else we will have issues during switchover.

select dest_id,process,transmit_mode,async_blocks, 
net_timeout,delay_mins,reopen_secs,register,binding 
from v$archive_dest; 

-- The following select will show any errors that occured the last time an attempt to
-- archive to the destination was attempted. If ERROR is blank and status is VALID then
-- the archive completed correctly.

column error format a80 tru 
select dest_id,status,error from v$archive_dest; 

-- Determine if any error conditions have been reached by querying the v$dataguard_status

column message format a100 
select message, timestamp 
from v$dataguard_status 
where severity in ('Error','Fatal') 
order by timestamp; 

-- The following query is ran to get the status of the Standby Redo Log's on the standby. If the
-- primary is archiving with the LGWR process and SRL's are present (in the correct
-- number and size) then we should see a group# active.

select group#,sequence#,bytes,used,archived,status from v$standby_log;

-- The above SRL's should match in number and in size with the Online Redo Log's returned below:

select group#,thread#,sequence#,bytes,archived,status from v$log; 

-- Query v$managed_standby to see the status of processes involved in the configuration.

select process,status,client_process,sequence#,block#,active_agents,known_agents
from v$managed_standby;

-- Verify that the last sequence# received and the last sequence# applied to standby
-- database.

select al.thrd "Thread", almax "Last Seq Received", lhmax "Last Seq Applied"
from (select thread# thrd, max(sequence#) almax
from v$archived_log
where resetlogs_change#=(select resetlogs_change# from v$database)
group by thread#) al,
(select thread# thrd, max(sequence#) lhmax
from v$log_history
where first_time=(select max(first_time) from v$log_history)
group by thread#) lh
where al.thrd = lh.thrd;

-- V$ARCHIVE_GAP displays information about archive gaps on a standby database.
-- This view can be used to find out the current archive gap that is blocking
-- recovery for the current recovery incarnation.

select * from v$archive_gap; 

-- It is always better to verify all non-default init parameters.

set numwidth 5 
column name format a30 tru 
column value format a50 wra 
select name, value 
from v$parameter 
where isdefault = 'FALSE';

spool off