We will check data guard status in SQL Plus in this article in many ways.
Check 1:
Check for LAG from V$DATAGUARD_STATS View.
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[Physical-1] SQL> set linesize 9000 [Physical-1] SQL> column name format a25 [Physical-1] SQL> column value format a20 [Physical-1] SQL> column time_computed format a25 [Physical-1] SQL> SELECT name, value, time_computed FROM v$dataguard_stats; NAME VALUE TIME_COMPUTED ------------------------- -------------------- ------------------------- transport lag +00 00:00:00 01/16/2017 14:18:49 apply lag +00 00:00:00 01/16/2017 14:18:49 apply finish time +00 00:00:00.000 01/16/2017 14:18:49 estimated startup time 29 01/16/2017 14:18:49 |
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[Logical-1] SQL> set linesize 9000 [Logical-1] SQL> column name format a25 [Logical-1] SQL> column value format a20 [Logical-1] SQL> column time_computed format a25 [Logical-1] SQL> SELECT name, value, time_computed FROM v$dataguard_stats; NAME VALUE TIME_COMPUTED ------------------------- -------------------- ------------------------- transport lag +00 00:00:00 01/16/2017 14:18:24 apply lag +00 02:01:50 01/16/2017 14:18:24 apply finish time 01/16/2017 14:18:24 estimated startup time 25 01/16/2017 14:18:24 |
Check 2:
It is also possible to see whether Redo Logs are sent and applied to Standby correctly or not, by following the Sequence numbers.
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[Primary-1 ]SQL> select max(sequence#),thread# from v$archived_log group by thread#; MAX(SEQUENCE#) THREAD# -------------- ---------- 27251 1 22326 2 |
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[Physical-1] SQL> select max(sequence#),thread#, applied from v$archived_log group by thread#, applied; MAX(SEQUENCE#) THREAD# APPLIED -------------- ---------- --------- 27250 1 YES 27251 1 IN-MEMORY 22326 2 YES |
Check 3:
The query below shows the latest archives on Primary and Standby. It shows the last archive produced in Primary and the last archive applied to Standby.
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SELECT a.resetlogs_id, DECODE (a.thread#, 1, 'node1', 2, 'node2') HOST, b.last_seq prmy_last_file, a.applied_seq stdby_last_file, CASE WHEN b.last_seq - a.applied_seq > 2 THEN '=>' ELSE to_char(b.last_seq - a.applied_seq) END archive_difference, TO_CHAR (a.latest_apply_time, 'dd/mm/yyyy hh24:mi:ss') stdby_latest_time FROM (SELECT resetlogs_id, thread#, MAX (sequence#) applied_seq, MAX (next_time) latest_apply_time FROM v$archived_log WHERE applied = 'YES' GROUP BY resetlogs_id, thread#) a, (SELECT resetlogs_id, thread#, MAX (sequence#) last_seq FROM v$archived_log GROUP BY resetlogs_id, thread#) b WHERE a.thread# = b.thread# ORDER BY a.thread#; |
Check 4:
It can be seen if there is an error in the Alert Log from V$DATAGUARD_STATUS View. An alarm can be created by selecting the “Error” column in the Severity column here.
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[Physical-2] SQL> column message format a66 [Physical-2] SQL> SELECT timestamp, facility, message FROM v$dataguard_status ORDER by timestamp; TIMESTAMP FACILITY MESSAGE --------- ------------------------ ------------------------------------------------------------------ 15-JAN-17 Log Apply Services Managed Standby Recovery not using Real Time Apply 16-JAN-17 Remote File Server RFS[50]: Assigned to RFS process 28009 16-JAN-17 Remote File Server Primary database is in MAXIMUM PERFORMANCE mode 16-JAN-17 Log Transport Services ARC5: Completed archiving thread 1 sequence 575 (0-0) 16-JAN-17 Log Transport Services ARC6: Beginning to archive thread 2 sequence 339 (6091863-6091873) 16-JAN-17 Log Transport Services ARC6: Completed archiving thread 2 sequence 339 (0-0) |
Check 5:
The status of Redo Apply and Redo Transport services can be seen from V$MANAGED_STANDBY View.
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[Primary-1] SQL> column group# format a10 [Primary-1] SQL> SELECT process, status, group#, thread#, sequence# FROM v$managed_standby order by process, group#, thread#, sequence#; PROCESS STATUS GROUP# THREAD# SEQUENCE# --------- ------------ ---------- ---------- ---------- ARCH CLOSING 1 1 561 ARCH CLOSING 1 1 565 ARCH CLOSING 1 1 569 ARCH CLOSING 1 1 573 ARCH CLOSING 1 1 575 ARCH CLOSING N/A 1 538 ARCH CLOSING N/A 1 561 ARCH CLOSING N/A 1 569 LGWR CLOSING 2 1 568 LNS WRITING 2 1 576 LNS WRITING 2 1 576 11 rows selected. |
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[Physical-1] SQL> column group# format a10 [Physical-1] SQL> SELECT process, status, group#, thread#, sequence# FROM v$managed_standby order by process, group#, thread#, sequence#; PROCESS STATUS GROUP# THREAD# SEQUENCE# --------- ------------ ---------- ---------- ---------- ARCH CLOSING 5 1 571 ARCH CONNECTED N/A 0 0 ARCH CONNECTED N/A 0 0 ARCH CONNECTED N/A 0 0 ARCH CONNECTED N/A 0 0 ARCH CONNECTED N/A 0 0 ARCH CONNECTED N/A 0 0 ARCH CONNECTED N/A 0 0 MRP0 APPLYING_LOG N/A 2 340 RFS IDLE N/A 0 0 RFS IDLE N/A 0 0 11 rows selected. |
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[Logical-1] SQL> column group# format a10 [Logical-1] SQL> SELECT process, status, group#, thread#, sequence# FROM v$managed_standby order by process, group#, thread#, sequence#; PROCESS STATUS GROUP# THREAD# SEQUENCE# --------- ------------ ---------- ---------- ---------- ARCH CLOSING 1 1 95 ARCH CLOSING 5 1 574 ARCH CLOSING 6 1 573 ARCH CLOSING 8 2 332 ARCH CLOSING 8 2 334 ARCH CLOSING 9 2 333 ARCH CLOSING 9 2 335 ARCH CONNECTED N/A 0 0 RFS IDLE N/A 0 0 RFS IDLE N/A 0 0 RFS IDLE N/A 0 0 PROCESS STATUS GROUP# THREAD# SEQUENCE# --------- ------------ ---------- ---------- ---------- RFS IDLE N/A 0 0 RFS IDLE N/A 0 0 RFS IDLE N/A 0 0 RFS IDLE N/A 0 0 RFS IDLE N/A 0 0 16 rows selected. |
NOTE: If you notice, there is no LSP process that performs Redo-Apply job in Logical Standby Databases as a result of the query. The reason is that v$managed_standby view is valid for Physical Standby Database.
Check 6:
The information of the transactions currently processed by SQL APPLY can be seen from the V$LOGSTDBY_TRANSACTION View.
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[Logical-1] SQL> SELECT primary_xid, type,mining_status, apply_status FROM v$logstdby_transaction; no rows selected |
Check 7:
It can be seen which archives are transmitted to the standby when.
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[Physical-1] SQL>select THREAD#,sequence#, round((blocks*block_size)/1024/1024), first_time, next_time, completion_time from gv$archived_log where REGISTRAR='RFS' order by 6; . . . THREAD# SEQUENCE# ROUND((BLOCKS*BLOCK_SIZE)/1024/1024) FIRST_TIM NEXT_TIME COMPLETIO ---------- ---------- ------------------------------------ --------- --------- --------- 1 79450 656 15-JAN-19 15-JAN-19 15-JAN-19 2 96900 665 15-JAN-19 15-JAN-19 15-JAN-19 2 96900 665 15-JAN-19 15-JAN-19 15-JAN-19 1 79451 655 15-JAN-19 15-JAN-19 15-JAN-19 1 79451 655 15-JAN-19 15-JAN-19 15-JAN-19 2 96901 667 15-JAN-19 15-JAN-19 15-JAN-19 2 96901 667 15-JAN-19 15-JAN-19 15-JAN-19 1866 rows selected. |
Check 8:
You can get information about Standby Redo Logs from V$STANDBY_LOG View by using the following queries.
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[Primary-1] SQL> set linesize 9000 [Primary-1] SQL> column dbid format a15 [Primary-1] SQL> SELECT group#, thread#, sequence#, dbid, archived, status FROM v$standby_log; GROUP# THREAD# SEQUENCE# DBID ARC STATUS ---------- ---------- ---------- --------------- --- ---------- 5 1 0 UNASSIGNED YES UNASSIGNED 6 1 0 UNASSIGNED YES UNASSIGNED 7 1 0 UNASSIGNED YES UNASSIGNED 8 2 0 UNASSIGNED YES UNASSIGNED 9 2 0 UNASSIGNED YES UNASSIGNED 10 2 0 UNASSIGNED YES UNASSIGNED 6 rows selected. |
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[Physical-1] SQL> set linesize 9000 [Physical-1] SQL> column dbid format a15 [Physical-1] SQL> SELECT group#, thread#, sequence#, dbid, archived, status FROM v$standby_log; GROUP# THREAD# SEQUENCE# DBID ARC STATUS ---------- ---------- ---------- --------------- --- ---------- 5 1 0 UNASSIGNED NO UNASSIGNED 6 1 576 1769705496 YES ACTIVE 7 1 0 UNASSIGNED NO UNASSIGNED 8 2 340 1769705496 YES ACTIVE 9 2 0 UNASSIGNED NO UNASSIGNED 10 2 0 UNASSIGNED YES UNASSIGNED 6 rows selected. |
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[Logical-1] SQL> set linesize 9000 [Logical-1] SQL> column dbid format a15 [Logical-1] SQL> SELECT group#, thread#, sequence#, dbid, archived, status FROM v$standby_log; GROUP# THREAD# SEQUENCE# DBID ARC STATUS ---------- ---------- ---------- --------------- --- ---------- 5 1 576 1769705496 YES ACTIVE 6 1 0 UNASSIGNED NO UNASSIGNED 7 1 0 UNASSIGNED NO UNASSIGNED 8 2 340 1769705496 YES ACTIVE 9 2 0 UNASSIGNED NO UNASSIGNED 10 2 0 UNASSIGNED NO UNASSIGNED |
The combinations of the ARCHIVED and STATUS columns in the above query mean the following;
ARC STATUS
| NO UNASSIGNED | Standby Redo Log has been archived and is suitable for reuse. |
| YES UNASSIGNED | Standby Redo Log has never been used and is ready for use. |
| NO ACTIVE | Shows that writing to Standby Redo Log is finished and Standby Redo Log is expected to be archived. |
| YES ACTIVE | Shows that Standby Redo Log is actively used and is not yet archived. |
Check 9:
In cases where Standby Database does not receive Redos, we should check V$ARCHIVE_DEST.
Query ARCHIVE DESTINATION.
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[Primary-1] SQL> SELECT dest_id,valid_type,valid_role,valid_now FROM v$archive_dest; DEST_ID VALID_TYPE VALID_ROLE VALID_NOW ---------- --------------- ------------ ---------------- 1 ALL_LOGFILES ALL_ROLES YES 2 ALL_LOGFILES PRIMARY_ROLE YES 3 ALL_LOGFILES PRIMARY_ROLE YES 4 ALL_LOGFILES ALL_ROLES UNKNOWN |
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[Physical-1] SQL> SELECT dest_id,valid_type,valid_role,valid_now FROM v$archive_dest; DEST_ID VALID_TYPE VALID_ROLE VALID_NOW ---------- --------------- ------------ ---------------- 1 ALL_LOGFILES ALL_ROLES YES 2 ALL_LOGFILES ALL_ROLES UNKNOWN |
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[Logical-1] SQL> SELECT dest_id,valid_type,valid_role,valid_now FROM v$archive_dest; DEST_ID VALID_TYPE VALID_ROLE VALID_NOW ---------- --------------- ------------ ---------------- 1 ALL_LOGFILES ALL_ROLES YES 2 ALL_LOGFILES ALL_ROLES UNKNOWN |
Values and meanings of the VALID_NOW column in this View are as follows;
| YES | This value shows that the Archive log destination has been defined and is valid for the current database role. Usually LOG_ARCHIVE_DEST_1 is defined this way. |
| WRONG VALID_TYPE | This value shows that the Archive log destination has been defined, but there are no Standby Logs to use when in Standby Role. |
| WRONG VALID_ROLE | This value shows that the Archive log destination is incorrectly defined. Online Logs cannot be read while in Standby Role. |
| UNKNOWN | This value shows that the Archive Log destination is not defined. |
Check 10:
If there are no problems in the destinations, errors are checked.
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[Primary-1] SQL> column destination format a30 [Primary-1] SQL> column error format a20 [Primary-1] SQL> set linesize 9000 [Primary-1] SQL> SELECT DEST_ID, STATUS, DESTINATION, ERROR FROM V$ARCHIVE_DEST WHERE DEST_ID <=5; DEST_ID STATUS DESTINATION ERROR ---------- --------- ------------------------------ -------------------- 1 VALID USE_DB_RECOVERY_FILE_DEST 2 VALID standby 3 VALID logical 4 INACTIVE 5 INACTIVE |
Check 11:
If there is no error, the following are checked.
- TNSNAMES.ORA file,
- LOG_ARCHIVE_DEST_n parameters,
- LOG_ARCHIVE_DEST_STATE_n parameters,
- LISTENER.ORA file,
- Whether Listener runs on Standby,
- Whether instances are running is checked on standby.
Queries to Check Standby
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SQL> SELECT SEQUENCE#,APPLIED FROM V$ARCHIVED_LOG ORDER BY SEQUENCE#; SEQUENCE# APPLIED ---------- --------- 10033 YES 10034 YES 10035 YES 10036 YES 10037 YES 10038 YES SQL> SELECT MESSAGE FROM V$DATAGUARD_STATUS; MESSAGE -------------------------------------------------------------------------------- ARCj: Beginning to archive thread 1 sequence 10037 (12423487630539-1242348971229 8) ARCj: Completed archiving thread 1 sequence 10037 (0-0) Media Recovery Log +FRA/mwstdbydb/archivelog/2015_12_29/thread_1_seq_10037.862.8 99733563 Media Recovery Waiting for thread 2 sequence 7938 (in transit) ARC0: Beginning to archive thread 2 sequence 7938 (12423487903683-12423490247632 ) MESSAGE -------------------------------------------------------------------------------- ARC0: Completed archiving thread 2 sequence 7938 (0-0) Media Recovery Log +FRA/mwstdbydb/archivelog/2015_12_29/thread_2_seq_7938.863.89 9734925 Media Recovery Waiting for thread 1 sequence 10038 (in transit) ARC1: Beginning to archive thread 1 sequence 10038 (12423489712298-1242349181804 2) ARC1: Completed archiving thread 1 sequence 10038 (0-0) Media Recovery Log +FRA/mwstdbydb/archivelog/2015_12_29/thread_1_seq_10038.864.8 99738951 MESSAGE -------------------------------------------------------------------------------- Media Recovery Waiting for thread 2 sequence 7939 (in transit) ARC3: Beginning to archive thread 2 sequence 7939 (12423490247632-12423492561200 ) ARC3: Completed archiving thread 2 sequence 7939 (0-0) Media Recovery Log +FRA/mwstdbydb/archivelog/2015_12_29/thread_2_seq_7939.865.89 9740831 Media Recovery Waiting for thread 1 sequence 10039 (in transit) SQL> select to_char(current_scn) from v$database; TO_CHAR(CURRENT_SCN) ---------------------------------------- 12423492561199 SQL> select scn_to_timestamp(1681797) from dual; PROD SCN_TO_TIMESTAMP(12423492561199) --------------------------------------------------------------------------- 29-DEC-15 04.00.31.000000000 PM SQL> select thread#, sequence#, status from v$log; PROD SCN_TO_TIMESTAMP(12423492561199) --------------------------------------------------------------------------- 29-DEC-15 04.00.31.000000000 PM SQL> select thread#, sequence#, status from v$log; THREAD# SEQUENCE# STATUS ---------- ---------- ---------------- 1 10038 INACTIVE 1 10039 INACTIVE 1 10040 CURRENT 1 10036 INACTIVE 1 10037 INACTIVE 2 7938 INACTIVE 2 7939 INACTIVE 2 7940 CURRENT 2 7936 INACTIVE 2 7937 INACTIVE SQL> select process, status, thread#, sequence#, block#, blocks from v$managed_standby; PROCESS STATUS THREAD# SEQUENCE# BLOCK# BLOCKS --------- ------------ ---------- ---------- ---------- ---------- ARCH CLOSING 2 7938 1613824 582 ARCH CLOSING 1 10038 1613824 648 ARCH CONNECTED 0 0 0 0 ARCH CLOSING 2 7939 1613824 510 ARCH CLOSING 1 10039 1613824 171 ARCH CLOSING 1 10030 1613824 1800 ARCH CLOSING 2 7931 1613824 796 ARCH CLOSING 2 7932 71680 1080 ARCH CLOSING 1 10031 829440 1043 ARCH CLOSING 2 7933 1613824 271 ARCH CLOSING 1 10032 1613824 38 PROCESS STATUS THREAD# SEQUENCE# BLOCK# BLOCKS --------- ------------ ---------- ---------- ---------- ---------- ARCH CLOSING 2 7934 1695744 239 ARCH CLOSING 1 10033 1613824 11 ARCH CLOSING 2 7935 1613824 191 ARCH CLOSING 1 10034 1613824 332 ARCH CLOSING 1 10035 1318912 497 ARCH CLOSING 2 7936 1230848 236 ARCH CLOSING 1 10036 1611776 1964 ARCH CLOSING 2 7937 1613824 70 ARCH CLOSING 1 10037 1613824 90 RFS IDLE 0 0 0 0 RFS IDLE 0 0 0 0 PROCESS STATUS THREAD# SEQUENCE# BLOCK# BLOCKS --------- ------------ ---------- ---------- ---------- ---------- RFS IDLE 1 10040 181017 1 RFS IDLE 2 7940 1204818 2 RFS IDLE 0 0 0 0 RFS IDLE 0 0 0 0 MRP0 WAIT_FOR_LOG 2 7940 0 0 SQL> select * from V$dataguard_Stats; NAME VALUE UNIT TIME_COMPUTED DATUM_TIME -------------------------------- ---------------------------------------------------------------- ------------------------------ ------------------------------ ------------------------------ transport lag +00 00:00:00 day(2) to second(0) interval 12/29/2015 17:02:32 12/29/2015 17:02:31 apply lag +00 01:02:00 day(2) to second(0) interval 12/29/2015 17:02:32 12/29/2015 17:02:31 apply finish time +00 00:00:04.884 day(2) to second(3) interval 12/29/2015 17:02:32 estimated startup time 45 second 12/29/2015 17:02:32 SQL> SELECT FIRST_TIME, TO_CHAR(FIRST_CHANGE#), TO_CHAR(NEXT_CHANGE#), SEQUENCE# FROM V$LOG_HISTORY; FIRST_TIM TO_CHAR(FIRST_CHANGE#) TO_CHAR(NEXT_CHANGE#) SEQUENCE# --------- ---------------------------------------- ---------------------------------------- ---------- 29-DEC-15 12423479700143 12423481704223 10033 29-DEC-15 12423481518592 12423483684832 7935 29-DEC-15 12423481704223 12423483761666 10034 29-DEC-15 12423483761666 12423485543281 10035 29-DEC-15 12423483684832 12423485543694 7936 29-DEC-15 12423485543281 12423487630539 10036 29-DEC-15 12423485543694 12423487903683 7937 29-DEC-15 12423487630539 12423489712298 10037 29-DEC-15 12423487903683 12423490247632 7938 29-DEC-15 12423489712298 12423491818042 10038 29-DEC-15 12423490247632 12423492561200 7939 |
