INDEX_BACKUP task for ZDLRA, Percentage done
Quick post how to check and identify done for INDEX_BACKUP task in ZDLRA. In one simple way, just to contextualize, INDEX_BACKUP is one task for ZDLRA that (after you input the backup of datafile) generate an index of the blocks and create the virtual backup for you.
Here I will start a new series about ZDLRA with some hints based on my usage experience (practically since the release in 2014). The post from today is just little scratch about ZDLRA internals, I will extend this post in others (and future posts), stay tuned.
INDEX_BACKUP
As told before this task is one of the most important for ZDLRA, but it can take a lot of time to index the backup if the file is huge (a lot of TB’). Think that ZDLRA need to index all the blocks for the file, and for the first level 0 this took some time.
Unfortunately, officially there is no way to check how far you are from the end and how much was already done to create the index. The table that shows you the info for running tasks doesn’t contain this information. Because of that, I created a little SQL that you can use to verify the task and try to discover the percentage of already done.
SQL
In the SQL I will use two tables from RASYS ZDLRA schema:
RA_TASK: The table RA_TASK list the tasks processed/in wait/running. Documented here (https://docs.oracle.com/cd/E88198_01/AMAGD/amagd_views.htm#AMAGD1440)
SESSION: Internal table for ZDLRA that store all the internal sessions running tasks and other things. This is not documented table/view.
The SQL:
SELECT s.ba_session_id, s.instance_id, s.sid, s.serial#, s.job_name
, rt.task_id, rt.DB_KEY, rt.db_unique_name, rt.task_type, rt.state, rt.waiting_on
, rt.elapsed_seconds
, gs.module, gs.sql_id, gs.action, gs.event
, rt.BP_KEY, rt.bs_key, rt.df_key, rt.vb_key
FROM sessions s
JOIN ra_task rt
ON rt.task_id = s.current_task
JOIN gv$session gs
ON gs.inst_id = s.instance_id
AND gs.sid = s.sid
AND gs.serial# = s.serial#
ORDER BY rt.LAST_EXECUTE_TIME DESC
This query is a join between RA_TASK, SESSION (from ZDLRA), and V$SESSION from DB side. As you can see, the link between RA_TASK and SESSION is the current task. And since you reach the SESSION info from ZDLRA, you can link with the sid, serial#, and inst_id running the task. Fortunately, the V$SESSION has the desired information. This query returns all running tasks, you can filter by task type if desired.
Look the result from one execution:
SQL> col JOB_NAME format a30
SQL> col STATE format a10
SQL> col DB_UNIQUE_NAME format a20
SQL> col MODULE format a30
SQL> col ACTION format a20
SQL> col EVENT format a35
SQL> col TASK_TYPE format a15
SQL> set linesize 400
SQL> l
1 SELECT s.ba_session_id, s.instance_id, s.sid, s.serial#, s.job_name
2 , rt.task_id, rt.DB_KEY, rt.db_unique_name, rt.task_type, rt.state, rt.waiting_on
3 , rt.elapsed_seconds
4 , gs.module, gs.sql_id, gs.action, gs.event
5 , rt.BP_KEY, rt.bs_key, rt.df_key, rt.vb_key
6 FROM sessions s
7 JOIN ra_task rt
8 ON rt.task_id = s.current_task
9 JOIN gv$session gs
10 ON gs.inst_id = s.instance_id
11 AND gs.sid = s.sid
12 AND gs.serial# = s.serial#
13* ORDER BY rt.LAST_EXECUTE_TIME DESC
SQL> /
BA_SESSION_ID INSTANCE_ID SID SERIAL# JOB_NAME TASK_ID DB_KEY DB_UNIQUE_NAME TASK_TYPE STATE WAITING_ON ELAPSED_SECONDS MODULE SQL_ID ACTION EVENT BP_KEY BS_KEY DF_KEY VB_KEY
------------- ----------- ---------- ---------- ------------------------------ ---------- ---------- -------------------- --------------- ---------- ---------- --------------- ------------------------------ ------------- -------------------- ----------------------------------- ---------- ---------- ---------- ----------
93729765 2 4453 42235 RA$_EXEC_93730430 93676068 477602 SIMON_DB1 INDEX_BACKUP RUNNING 28558.1086 q_restore_fast brt6uuhzacdnu plan 12% done cell single block physical read 41032043
SQL>
Columns import here:
ACTION: from GV$SESSION show the percentage already done for this INDEX_BACKUP task.
ELAPSED_SECONDS: from RA_TASK, show seconds that this task is running. You can use together with the percentage and try to figure out the time to reach 100%.
BP_KEY/DF_KEY/BS_KEY/VB_KEY: from RA_TASK, show base info from what is the input to task. In this case, and usually, for INDEX_BACKUP tasks the only column will be BP_KEY (that represent the backup piece key id) because you are indexing a new backup that entered in the ZDLRA.
As you can see, the INDEX_BACKUP task 93676068 for the backup piece 41032043 took 28558 seconds and it is running without a wait and processed 12% of the backup piece. We can dig a little more try to identify and validate some values from blocks processed, but I will cover in the second part.
Conclusion
As you can see, with this simple query you can check the percentage done for the INDEX_BACKUP task. Was needed to query some internal tables of database, but the desired result was easy to find. I tested this query with old version of ZDLRA (12.2.1.1.1-201805 from August of 2018) and with the last version (12.2.1.1.2-201907 from 11/July) and the result was the same, and always accurate.
I will post more about ZDLRA, from usage experience to internal details.
You can check my presentation at OOW 2015 about my MAA project that used ZDLRA to protect all environment: https://www.oracle.com/technetwork/database/availability/con8830-zdlradeepdive-2811109.pdf
Disclaimer: “The postings on this site are my own and don’t necessarily represent my actual employer positions, strategies or opinions. The information here was edited to be useful for general purpose, specific data and identifications were removed to allow reach the generic audience and to be useful for the community.”
