Troubleshooting of Oracle Dataguard

Troubleshooting of Standby Database

There are many times when we need to troubleshoot dataguard status and we want to know if standby databases are in SYNC or not.

Below are few SQL queries which are very useful to troubleshoot any problem with log archives which needs to be applied to standby database

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Select ('Database named '||name||' is '||open_mode||' and is in '||database_role||' role') as "DATABASE_INFO" from v$database;


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select ' ' from dual;
select '#################### RECOVERY_INFO ###################' from dual;
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col host_name for a20
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Select distinct i.instance_name, i.host_name, r.inst_id, r.recovery_mode from gv$archive_dest_status r, gv$instance I where i.inst_id=r.inst_id and r.recovery_mode <> 'IDEL';


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select ' ' from dual;
select '#################### GAP_INFO ######################' from dual;
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select process, client_process, status, thread#, sequence# from gv$managed_standby where thread#<>0 and process like 'MRP%';


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select ' ' from dual;
select '################### LOG_APPLY_INFO ###################' from dual;
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Select thread#, max(sequence#), applied from v$archived_log where applied = 'YES' group by thread#, applied;


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select ' ' from dual;
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select '---------------------------------------------------------------------------------' from dual;
Select 'Please apply the log sequence '||sequence#||' of thread '||thread#||'.' from gv$managed_standby where thread#<>0 and status like 'WAIT%';
Select 'MRP0 is '||status||' successfully' from gv$managed_standby where thread#<>0 and status like 'APPL%';
select '---------------------------------------------------------------------------------' from dual;
select 'Archive log sequence '||sequence#||' is not yet archived on primary side also.' from v$archived_log where thread#=(select thread# from v$managed_standby where status like 'WAIT%') and sequence#=(select sequence# from v$managed_standby where status like 'WAIT%');
select 'Archive log sequence '||sequence#||' is not yet archived on primary side also.' from v$archived_log where thread#=(select thread# from v$managed_standby where status like 'WAIT%') and archived='NO';
select ' ' from dual;
select '-----Storage Info----' from dual;


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Select 'INFO 1: The standby destination '||name||' is of '||round((Total_mb/1024), 0)||' GB, among this '||round((Free_mb/1024), 0)||' GB is free and '||round(((((Total_mb/1024)-(Free_mb/1024))/(Total_mb/1024))*100), 0)||'% is used.' from v$asm_diskgroup where name=(select trim('+' from value) from v$parameter where name='standby_archive_dest');

Select 'INFO 2: Storage if fine.' From v$asm_diskgroup where name=(select trim('+' from value) from v$parameter where name='standby_archive_dest') and free_mb>((Total_mb/100)*8);

Select 'INFO 2: WARNING: Storage has only '||round(100-((((Total_mb/1024)-(Free_mb/1024))/(Total_mb/1024))*100), 0)||'% Percentage free space.' From v$asm_diskgroup where name=(select trim('+' from value) from v$parameter where name='standby_archive_dest') and free_mb<((Total_mb/100)*8);

Select 'INFO 2: CRITICAL: Space need to be freed from storage because standby destination is 100% full.' From v$asm_diskgroup where name=(select trim('+' from value) from v$parameter where name='standby_archive_dest') and total_mb=(total_mb-free_mb);


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!rm create_space_standby.rcv
!rm create_space_standby.sql
select 'NOTE: System is About to create Rman rcv file "create_space_standby.rcv".' from dual;
Spool create_space_standby.rcv
Select 'run {' from dual;
Select 'crosscheck archivelog all;' from dual;
select 'delete noprompt archivelog sequence between '||min(sequence#)||' and '||max(sequence#)||' thread '||thread#||';' from v$archived_log where applied='YES' and deleted='NO' group by thread#, applied, deleted;
select '}' from dual;
select 'exit' from dual;


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select 'Rman will automatically start creating the space if archive destination usage is above 50%.' From v$asm_diskgroup where name=(select trim('+' from value) from v$parameter where name='standby_archive_dest') and free_mb<((total_mb/100)*50);


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alter session set nls_date_format='ddmmyyyy_HHMI';
spool create_space_standby.sql
select '!rman target / cmdfile create_space_standby.rcv log Log_standby_purge_'||sysdate||'.log' From v$asm_diskgroup where name=(select trim('+' from value) from v$parameter where name='standby_archive_dest') and free_mb<((total_mb/100)*50);
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@create_space_standby.sql
select ' To manually create space in Standby destination execute latest RMAN file create_space_standby.rcv' from v$asm_diskgroup where name=(select trim('+' from value) from v$parameter where name='standby_archive_dest') and total_mb=(total_mb-free_mb);
select ' To manually create space in Standby destination execute latest RMAN file create_space_standby.rcv' from v$asm_diskgroup where name=(select trim('+' from value) from v$parameter where name='standby_archive_dest') and free_mb<((Total_mb/100)*8);


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col name for a10
PROMPT ***** Disk Group Details under ASM control ****
select NAME , TYPE, TOTAL_MB, FREE_MB, round(FREE_MB/TOTAL_MB * 100,1) PCT_FREE,BLOCK_SIZE, SECTOR_SIZe, OFFLINE_DISKS, STATE from v$asm_diskgroup;
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###############################
# BACKUP_INFO
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ALTER SESSION SET NLS_DATE_FORMAT='yyyymmdd HH:MI';
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Col tag for a10
Col COMPRESSED for a11
Col DEVICE_TYPE for a12
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Select '-----Tags--------' from dual;
Select distinct tag from V$BACKUP_PIECE_DETAILS where tag like 'ARCH%' or tag like '%LEV1' or tag like '%LEV0' or tag like 'CNTR%' or tag like 'SP%';
Select ' ' from dual;
Select ' ' from dual;
Select '--------PLEASE CHOOSE Tag FROM ABOVE:-------' from dual;
Select ' ' from dual;
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col Media for a10
col START_TIME for a14
col COMPLETION_TIME for a14
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select BS_KEY, DEVICE_TYPE, nvl(media,'---X---') as "Media" , TAG, STATUS status, START_TIME, COMPLETION_TIME, round((ELAPSED_SECONDS/60/60), 0) Hours, round((bytes/1024/1024/1024), 0) as "GB", COMPRESSED, DELETED from V$BACKUP_PIECE_DETAILS where tag=upper('&Tag') and deleted='NO' order by device_type, COMPLETION_TIME, deleted;
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Select ' ' from dual;
select '-------BACKUP INFO FOR L0, L1, AO BACKUPS-------' from dual;
select ' Last Level0 backup is completed on "'||completion_time||'.' from V$BACKUP_PIECE_DETAILS where BS_KEY=(select max(BS_KEY) from V$BACKUP_PIECE_DETAILS where tag='DB_LEV0');
Select ' ' from dual;
select ' Last Level1 backup is completed on "'||completion_time||'.' from V$BACKUP_PIECE_DETAILS where BS_KEY=(select max(BS_KEY) from V$BACKUP_PIECE_DETAILS where tag='DB_LEV1');
Select ' ' from dual;
select ' Last ARCHIVE Only backup is completed on "'||completion_time||'.' from V$BACKUP_PIECE_DETAILS where BS_KEY=(select max(BS_KEY) from V$BACKUP_PIECE_DETAILS where tag='ARCH_ONLY');
select ' ' from dual;
Select ' ' from dual;
select '>>>>>>>>This information is only for reference purpose.<<<<<<<<' from dual;
Select ' ' from dual;
select '>>>>>>>>FINISH<<<<<<<<<<' from dual;
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select ' ' from dual;
select '******************************' from dual;