Automatic Graceful Shutdown and Consistent Startup Method for Oracle DB on Linux

Hi all,

This is quite a common question whenever I arrive on any new company. The things is, there are more then one way to implement this depending on your environment, licensing and version.

So I decided to compile here some sort of summary for this:

1. Prefer to use Oracle Restart
This is the automated and validated method provided by Oracle, however it can be a bit confusing in some items which can lead us to think it’s not working. Here is a summary of the the configuration I recommend:

a) Configure database management to AUTOMATIC on SRVCTL

srvctl modify database -y AUTOMATIC
  • If AUTOMATIC (the default), the database is automatically restored to its previous running condition (started or stopped) upon restart of the database host computer.
  • If MANUAL, the database is never automatically restarted upon restart of the database host computer.

Refhttps://docs.oracle.com/cd/E11882_01/server.112/e25494/restart.htm#BABHHAHI

b) Set AUTO_START=always on CRSCTL

crsctl modify resource ora.grepora.db -attr AUTO_START=always
  • ALWAYS: Restarts the resource when the server restarts regardless of the state of the resource when the server stopped.
  • RESTORE: Restores the resource to the same state that it was in when the server stopped. Oracle Clusterware attempts to restart the resource if the value of TARGET was ONLINE before the server stopped.
  • NEVER: Oracle Clusterware never restarts the resource regardless of the state of the resource when the server stopped.

NOTE: On Oracle 11.2, the database auto start policy in the clusterware is restore, which means that clusterware will remember the last state of the database. As well as database, Oracle 11.2 comes by default with several important resources with attribute AUTO_START=restore in the profile.

NOTE2: 12c on you might need to use the flag “-unsupported” on command above (crsctl modify resource ora.grepora.db -attr AUTO_START=always – unsupported).

Refhttps://docs.oracle.com/cd/E11882_01/rac.112/e41959/resatt.htm#CHDFFEHJ

Observation: This is recommended for all the required components managed by those tools, like databases, asm, listener, diskgroups, etc.
I wrote an article about it with an script that I made by my own and can help you: https://grepora.com/2018/08/22/services-not-starting-automatically-with-crs-after-reboot/

A common problem: “I set the SRVCTL to Automatic, but databases still not starting automatically’.”
Explanation: When database Management policy is configured as AUTOMATIC and the resource of the database parameter AUTO_START is configured as restore, the cluster will restore its last state, because the cluster level is the first in the chain of commands, it overrides the database.

c) Save desired state of Pluggable Databases in case of Multitenant:
With the PDB in desired state, save it with command below:

ALTER PLUGGABLE DATABASE pdb1 SAVE STATE;

When the CDB start, it will bring the pdbs to it saved states.

2. As second Option, Oracle Provided Scripts

Oracle has some scripts to automate it in a standard and supported way. This is documented for 12.1 in Stopping and Starting Oracle Software.

NOTES:

  • Oracle 11gR2 documentation states the use of the dbstart and dbshut scripts are deprecated. It’s supposed to be replaced by Oracle Restart.
  • The Oracle 12c documentation has no mention of the deprecation of dbstart and dbshut and has reinstated the documentation about them (as I linked above). So, feel free to use dbstart and dbshut in a supported manner for all versions of the database.

I also wrote an article about those, with some info and scripts: https://grepora.com/2017/11/22/how-to-setup-automatic-startup-and-shutdown-of-an-oracle-database-on-linux-not-using-oracle-restart/

Observation: Item 1.c is still recommended here.

3. Community proven scripts

As a third option, we would have some community scripts, which are usually proven and doesn’t require us to remember or to code everything. I’d use some additional time reviewing and testing them though, as they are not Oracle provided/supported.

In general, I’d recommend the material produced by Tim Hall (Oracle Base): https://oracle-base.com/articles/linux/automating-database-startup-and-shutdown-on-linux

He has additional articles that may help for other versions:

  • Automating Shutdown and Startup (12.2)
  • Automating Shutdown and Startup (12.1)
  • Automating Shutdown and Startup (11.2)
  • Automating Shutdown and Startup (10.2)
  • Automating Startup and Shutdown (10.1)
  • Automating Database Startup and Shutdown (9.2)
  • Linux Services (systemd, systemctl)

 

Some Additional Twists:

  • The Oracle Restart configuration assume the CRS is left “enabled”. Disabling it means we don’t want it to start automatically. So, if you want the CRS to start with your server, it need to be enabled. After this, to start targets, depend on configurations as per mentioned on my previous post.
  •  Oracle will no execute any rpm change or relink automatically, as this is not part of any “restart” process. It may be required due any configuration change or corruption, and it cannot be automated.
  • Regarding gracefulness, it depends on the configuration you have on your SRVCTL too. It’s configured using stop and start option, as per example below:
srvctl modify database -d [db_unique_name] -s [start_options] -t [stop_options]
  • So for your case, it seems to me a complete command containing what was recommended on my previous post PLUS gracefulness, it would be:
srvctl modify database -d [db_unique_name] -s OPEN -t IMMEDIATE -y automatic

(Note the SRVCTL syntax can very on the versions. This one is valid for 11.2).

I hope this helps you on understanding the process.

See you next time!

AWS: ALTER SYSTEM and Managing SYS Objects in RDS

I’m very often managing services over EC2 and there are a few actions clients are often getting some issues to perform in RDS. So I decided to list here 5 of them:

Kill sessions:

begin
rdsadmin.rdsadmin_util.kill(
sid => &sid,
serial => &serial,
method => 'IMMEDIATE');
end;
/

Flush shared_pool or buffer_cache:

exec rdsadmin.rdsadmin_util.flush_shared_pool;
exec rdsadmin.rdsadmin_util.flush_buffer_cache;

Grant Privileges to SYS Objects

# Grant

begin
    rdsadmin.rdsadmin_util.grant_sys_object(
        p_obj_name  => 'V_$SESSION',
        p_grantee   => 'GREPORA',
        p_privilege => 'SELECT');
end;
/

# Grant with Grant Option

begin
    rdsadmin.rdsadmin_util.grant_sys_object(
        p_obj_name     => 'V_$SESSION',
        p_grantee      => 'GREPORA',
        p_privilege    => 'SELECT',
        p_grant_option => true);
end;
/

# Revoke

begin
    rdsadmin.rdsadmin_util.revoke_sys_object(
        p_obj_name  => 'V_$SESSION',
        p_revokee   => 'GREPORA',
        p_privilege => 'SELECT');
end;
/

 

Hope it Helps!

Review: Oracle Application Express Hands-On

Hi all,

I just want to thank you all for the attendance on the meetup promoted by GUOB last October 7th and 9th at São Paulo/SP and Brasilia/DF – Brazil!

And a special high five for our speakers on the days: Monica Godoy and Anderson Ferreira!

It was a pleasure to have you there and we can barely wait for the next one!

Oracle Application Express Hands-On in Brasília!

Hello all!

I’m happy to announce here the next GUOB Meetup in Brasília focused on APEX .

The meeting will be conducted by

When?
Next October 9th!
2PM to 6PM

Where?
Ed. Corporate Financial Center (Oracle).
Setor Comercial Norte Q 2 – North Wing, Brasilia – Federal District

Cost? FREE
Just confirm you presence here.

IMPORTANT: bring your laptop.

Agenda:
2PM – Autonomous Database and Oracle Application Express – Monica Godoy
4PM – Coffee-break
4:30PM – Dynamic Actions in Action – Anderson Ferreira
5:30PM – Open Mic
6PM – Closure

NewScreenshot 2019-09-23 às 16.42.37

Oracle Application Express Hands-On in São Paulo!

Hello all!

I’m happy to announce here the next GUOB Meetup in São Paulo focused on APEX .

The meeting will be conducted by Monica Godoy, Product Manager do Oracle Application Express.

When?
Next October 7th!
6PM to 8PM

Where?
Rua Dr. José Áureo Bustamante, 455

Cost? FREE
Just confirm you presence here.

IMPORTANT: bring your laptop.

Agenda:
6PM – Autonomous Database and Oracle Application Express – Monica Godoy
7:30PM – Open Mic
8PM – Closure

NewScreenshot 2019-09-23 às 16.48.00

Oracle Container for Kubernetes Hands-On – Porto Alegre

Hello all!

I’m happy to announce here the next Meetup in Porto Alegre speaking over Oracle Container for Kubernetes  and how Oracle works with Cloud Native.

The meeting will be conducted by Diogo Shibata, from Oracle.

When?
Next October 2nd!

Where?
ATTIVE Coworking – Rua Carlos Gardel nº 55 – Bela Vista – Porto Alegre

Cost? FREE
Just confirm you presence here.

IMPORTANT: bring your laptop.

WhatsApp Image 2019-09-23 at 22.54.55.jpeg

guobguors

Getting Oracle version – new utility on 18c oraversion

While scripting on an environment with different Oracle versions, I often needed to get the Oracle version for the target database as usually the SQL to be executed is version depended.

I used different methods to grab the database  version some you can see below:

SQL> select 
substr(
substr(
banner, 
instr(banner,' ',-(length(banner)-instr(banner,'.')),1)+1, 
instr(banner,' ',+instr(banner,'.'),1)-instr(banner,' ',-(length(banner)-instr(banner,'.')),1)-1
),
1, 
instr(
substr(
banner, 
instr(banner,' ',-(length(banner)-instr(banner,'.')),1)+1,
instr(banner,' ',+instr(banner,'.'),1)-instr(banner,' ',-(length(banner)-instr(banner,'.')),1)-1
),
'.'
)-1
) version
from v$version
where rownum = 1
; 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

VERSION
--------------------------------------------------------------------------------
18

Or like this

SQL> select substr(version,1,instr(version,'.')-1) version from product_component_version where product like 'Oracle%';

VERSION
--------------------------------------------------------------------------------
18

But on Oracle 18c there is a new utility called oraversion which you can get the same result as the above queries.

[oracle@server01 ~]$ oraversion
This program prints release version information.
These are its possible arguments:
-compositeVersion: Print the full version number: a.b.c.d.e.
-baseVersion: Print the base version number: a.0.0.0.0.
-majorVersion: Print the major version number: a.
-buildStamp: Print the date/time associated with the build.
-buildDescription: Print a description of the build.
-help: Print this message.
[oracle@server1 ~]$

[oracle@server01 ~]$ oraversion -majorVersion
18
[oracle@server01 ~]$

This could be somewhat useful but I though it was worth sharing.

Until next time.

Elisson Almeida

Restore table statistics using dbms_stats

Hi all, another quick as reference. Table statistics as everyone knows are  very important when the CBO is creating the execution plan. When you have new statistics Oracle will invalid the current execution plans affected by them and create new execution plans based on the new statistics. Most of the time it gets right  if that causes your execution plan to change for worse?

In this situations dba_tab_stats_history   view and dbms_stats.restore_table_stats procedures are your friends.

To validate set and check and set the stats history:

select dbms_stats.get_stats_history_retention from dual; 
exec dbms_stats.alter_stats_history_retention(30);

On dba_tab_stats_history you can view the last statistics available:

select table_name, stats_update_time, from dba_tab_stats_history where table_name='TABLE1' and owner='USER' order by 2 desc;

Use the dbms_stats.restore_table_stats to restore the statistics:

exec dbms_stats.restore_table_stats(ownname=>'USER',tabname=>'TABLE1',AS_OF_TIMESTAMP=>'DATE from column STATS_UPDATE_TIME on dba_tab_stats_history');

Hope it helps!

Elisson Almeida

Oracle: Explicitly Lock a Table

Hello all,
So I client had a process that kept need big chunks locks on a table. Problem is that due application use this lock occasionally failed (lock timeout) and the whole process fail. So how to guarantee this?

Using explicit locks for the table before starting the procedure, with command below:

LOCK TABLE GREPORA.GREP_TABLE IN SHARE MODE;

This lock is released as soon as the session commit or rollback transaction in the current session. Killing session means an implicit rollback, as usual.

The SHARE permits concurrent queries but prohibits updates to the locked table.

Nice right?
Hope it helps you too!

OEM Report: Last 6 month Database Space Usage and Growth

Hello All!
So I had worked in some very useful reports to have in OEM. In next weeks I’ll share some code you may like… 🙂

To create it? Enterprise -> Reports -> Information Reports. There are several nice default reports there you me like.

Now, let’s go to the first Report, as per title:

1. First you Select the Database:

Select_DB.png

2. Then you see the report:

Report3

That’s nice, right?
Here is a report for another database with actual 640GB average growth per month (its expected, once DBSize is over 60TB):

Growth

So, Mat, can you share the queries? Of course:

More“OEM Report: Last 6 month Database Space Usage and Growth”