Category: Database

Cloud Services | Exadata | Linux, Database, Oracle Engineered Systems | Exadata

Reduce Exadata Core Count

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Ok, so I was preparing for a DC services migration with a client and this would involve resizing the CPU count of Exadatas for better attending those services. This way, one of the steps will require reduce CPU counts in one of the sites to be aligned with the license terms.

Checking for the steps to accomplish that, I found references to change CPU and core count, but always described in the case of increasing allocation. As per 2.7 Increasing the Number of Active Cores on Database Servers. But not so much about reducing, as this seems to be unusual…

Also considering that the planned change would be within the minimum number requirement: 2.1 Restrictions for Capacity-On-Demand on Oracle Exadata Database Machine.

Reviewing on MOS, we found the When Attempting to Change the Number of Cores, Errors With: DBM-10004 – Decreasing the Number of Active Cores is not Supported ( Doc ID 2177634.1 ), pointing to use the clause “FORCE” on “ALTER DBSERVER pendingCoreCount =x” command.

And this worked. I just disabled the iaasMode to play safe. Have a look:

[root@grepora01~]# dbmcli
DBMCLI: Release  - Production on Mon Jan 05 01:10:12 EEST 2019
Copyright (c) 2007, 2014, Oracle.  All rights reserved.
DBMCLI> LIST DBSERVER attributes coreCount
	 36/44
DBMCLI> ALTER DBSERVER pendingCoreCount = 24 force
DBM-10022: At least 26 physical cores need to be active in order to support IaaS.
DBMCLI> ALTER DBSERVER iaasMode = "off"
DBServer exadb01 successfully altered
DBMCLI> ALTER DBSERVER pendingCoreCount = 24 force
DBServer grepora01 successfully altered. Please reboot the system to make the new pendingCoreCount effective.
DBMCLI> LIST DBSERVER attributes pendingCoreCount
24/44

–> Restart the server
After restarting, it should look like:

DBMCLI> LIST DBSERVER attributes coreCount
	 24/44
DBMCLI> LIST DBSERVER attributes pendingCoreCount

Hope this helps!

Database, SQL | PLSQL

Oracle: Easily Decoding ROWID

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Hi all,
Recently I needed to decode the rowid so I could find some information about it, I found this bit of code that I thought useful:

SET SERVEROUTPUT ON
DECLARE
v_rid VARCHAR2(20) ;
v_type NUMBER;
v_obj NUMBER;
v_rfno NUMBER;
v_bno NUMBER;
v_rno NUMBER;
BEGIN
v_rid := 'AAAAASAABAAAADxAAb';
dbms_output.put_line('Row_ID = "'||v_rid||'"');
dbms_rowid.rowid_info(CHARTOROWID(v_rid), v_type, v_obj, v_rfno, v_bno, v_rno);
IF v_type = 0 THEN
dbms_output.put_line('RowID Type -> Restricted');
ELSE dbms_output.put_line('RowID Type -> Extended');
END IF;
dbms_output.put_line('Object ID = "'||v_obj||'"');
dbms_output.put_line('Relative File Number = "'||v_rfno||'"');
dbms_output.put_line('Block Number = "'||v_bno||'"');
dbms_output.put_line('Row Number = "'||v_rno||'"');
END;
/

Note that I have hard-coded the rowid but it is relatively easy to either edit this or indeed to incorporate this into a procedure.

Here’s the sample output

Row_ID = "AAAAASAABAAAADxAAb"
RowID Type -> Extended
Object ID = "18"
Relative File Number = "1"
Block Number = "241"
Row Number = "27"

Hope this helps!
Cheers!

Database, Security

11g Improvements: New Grants

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Hi All!
I was reviewing some features in Oracle and, basically, every single time I review them I find something new. Seems Oracle Databases’ features are near to infinite and we frequently find some that can really add value to our solutions.

So I decided to make a serie of posts with really quick notes about some of them.
You can see all posts in this serie in my page of posts and some others more.

Ready? Here it goes, today actually 2 small things:

Execute Grant on Directories

In 10g was possible to grant READ and/or WRITE, but this also allowed executing the ORACLE_LOADER access driver. In 11g, only a user that has been given EXECUTE access to the directory object is allowed to run programs in it. This should be granted using:

grant EXECUTE on DIR_EXAMPLE;

DATABASE_ROLE constant for SYS_CONTEXT

In 11g the context procedure can also give DATABASE_ROLE, as it might be used as check for certain procedures to run only on standbys or to avoid it, for example.

Between values are: PRIMARY, PHYSICAL STANDBY, LOGICAL STANDBY and SNAPSHOT STANDBY. This can be executed this way:

SELECT sys_context('USERENV', 'DATABASE_ROLE') FROM dual;

You probably know about that, right?
Anyway, always good to remember!

Cheers!

Enterprise Manager, Errors and Bugs

OEM Information Reports: ORA-00600 [kpndbcon-svchpnotNULL]

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Having this error from an Information Report?

ORA-00600 [kpndbcon-svchpnotNULL]
ORA-00600: internal error code, arguments: [kpndbcon-svchpnotNULL], [], [], [], [], [], [], [], [], [], [], []

Don’t worry… Basically this is not an Oracle direct issue , the cause of this error is that while the report is running (it takes 2 or 3 minutes) one of the following happens:

  • The Database Session in the OEM Repository (Database Repository) is killed.
  • The Database Session in the Target Database (where OEM has to connect and get the data) is killed.
  • There is network issues between OEM Repository and the Target database causing “time outs” or that the session finishes erroneously. .
  • High workload in one database causes “time out” making the session finished erroneously.
  • So basically this is a communication problem, between the OEM Repository and the database from where the data is being gotten.
  • To keep reports like this running with database links is something that Oracle doesn’t support at all because of any network issue can cause that the report gets errors, you can read the following notes:

Some reference about it:

  • ORA-00600 [kpndbcon-svchpnotNULL] Errors (Doc ID 1615517.1)
  • ORA-00600 [kpndbcon-svchpnotNULL] query through dblink (Doc ID 1490700.1)
  • Information Publisher Report fails with Error Rendering Element. Exception: ORA-00600 [kpndbcon-svchpnotNULL] (Doc ID 1930280.1)


So what’s the solution?
The solution here is easy, just re-run it.

Hope it helps. Cheers!

Database, SQL | PLSQL

Oracle Top Growing Segments

This is the second post of a serie. First one here.

Now that you already have an idea regarding the size of the database top segments (first post), you might want to check the top growing segments, considering a specified number of days back.

You probably used some AWR information in past or generated an AWR report, at least. But if this is still new to you, AWR stands for Automatic Workload Repository. AWR is a built-in repository, used to collect, process, and maintain performance statistics for problem detection and self-tuning purposes. This gathered data is stored both in memory and in the database, and is displayed in both reports and views.

For additional information, you can check this official doc here.

We are going to use some AWR views:
– dba_hist_seg_stat: historical information captured from V$SEGSTAT about segment-level statistics.
– dba_hist_seg_stat_obj: names of the segments captured in the workload repository.

More“Oracle Top Growing Segments”

Database, SQL | PLSQL

Disable/Enable Maintenance Jobs

Hi all!
A couple days ago a client asked me assistance to disable all the maintenance jobs on DB to run a critical process.

First considerations: We could just disable window changing, once the jobs are related to windows, and Resource Manager Plans use to be as well. However, to answer the question directly:

# To disable/enable all maintenance jobs in from/for all windows:

EXEC DBMS_AUTO_TASK_ADMIN.disable;
EXEC DBMS_AUTO_TASK_ADMIN.enable;

# And to disable/enable specific maintenance jobs from/for all windows:

exec DBMS_AUTO_TASK_ADMIN.DISABLE('AUTO OPTIMIZER STATS COLLECTION',NULL, NULL);
exec DBMS_AUTO_TASK_ADMIN.DISABLE('AUTO SPACE ADVISOR',NULL, NULL);
exec DBMS_AUTO_TASK_ADMIN.DISABLE('SQL TUNING ADVISOR', NULL, NULL);

exec DBMS_AUTO_TASK_ADMIN.ENABLE('AUTO OPTIMIZER STATS COLLECTION',NULL, NULL);
exec DBMS_AUTO_TASK_ADMIN.ENABLE('AUTO SPACE ADVISOR',NULL, NULL);
exec DBMS_AUTO_TASK_ADMIN.ENABLE('SQL TUNING ADVISOR', NULL, NULL);

More information and details about it can be taken from here: https://docs.oracle.com/cd/E11882_01/server.112/e25494/tasks.htm#ADMIN11836

Hope it helps. Cheers!

Database, RAC | Data Guard

Exadata Compute Node Not Starting after a long Period…

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Well,
After a long time on a graceful reboot, the compute node was simply not starting… What do to?
The best is:

1. Connect to ILOM Console:

Go to: Host Management –> Power control –> select Power Cycle in drop down list.

2. Connect to ILOM Server start SP console:
You may do it from another node, of course.

[root@grepora02 ~]# ssh root@grepora01-ilom Password:

Oracle(R) Integrated Lights Out Manager

Version 3.2.9.23 r116695

Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

Warning: HTTPS certificate is set to factory default.

Hostname: grepora01-ilom

-> start /SP/console Are you sure you want to start /SP/console (y/n)? y

And, if not, as always, create a SR and follow with Oracle is the best way to go…

Hope it helps!

Cloud Services, Cloud Services | Exadata | Linux, Database

Creating a Free Oracle Database at AWS

Have you ever heard about Amazon RDS?

Amazon RDS is a Relational Database cloud based service, which intends to help you to automate administrative tasks like hardware provisioning, database creation, backups, etc. Currently six database engines are available under this service: Oracle Database, Microsoft SQL Server, Amazon Aurora, PostgreSQL, MySQL and MariaDB.

This post provides a quick step-by-step on how to create your first Oracle Database RDS.

Requirements:
– Have an Amazon AWS account. If you don’t have one, don’t panic! You can still create one at: https://portal.aws.amazon.com/gp/aws/developer/registration/index.html

Now, how to create a RDS? Here it goes:

More“Creating a Free Oracle Database at AWS”

Database, Enterprise Manager

OEM after a Maintenance: A memory component is suspected of causing a fault with a 100% certainty. Component Name : % Fault class : fault.memory.intel.dimm_ce

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Hi all!
So, I had this message from a memory component in my Exadata:

Message=A memory component is suspected of causing a fault with a 100% certainty. Component Name : /SYS/MB/P0/D3 Fault class : fault.memory.intel.dimm_ce

But this was right after a maintenance on server. Checking on ILOM:

-> show /SYS/MB/P0/D3

 /SYS/MB/P0/D3
    Targets:
        PRSNT
        SERVICE

    Properties:
        type = DIMM
        ipmi_name = MB/P0/D3
        fru_name = 16384MB DDR4 SDRAM DIMM
        fru_manufacturer = Samsung
        fru_part_number = %
        fru_rev_level = 01
        fru_serial_number = %
        fault_state = OK
        clear_fault_action = (none)

Checking on CellCLI alert history:

CellCLI> list alerthistory detail

	 name:                   13_1
	 alertDescription:       "A memory component suspected of causing a fault"
	 alertMessage:           "A memory component is suspected of causing a fault with a 100% certainty.  Component Name : /SYS/MB/P0/D3  Fault class    : fault.memory.intel.dimm_ce  Fault message  : http://support.oracle.com/msg/SPX86A-8002-XM"
	 alertSequenceID:        13
	 alertShortName:         Hardware
	 alertType:              Stateful
	 beginTime:              %
	 endTime:                %
	 examinedBy:             
	 metricObjectName:       /SYS/MB/P0/D3_FAULT
	 notificationState:      1
	 sequenceBeginTime:      %
	 severity:               critical
	 alertAction:            "For additional information, please refer to http://support.oracle.com/msg/SPX86A-8002-XM Automatic Service Request has been notified with Unique Identifier: %.  Diagnostic package is attached. It is also accessible at % It will be retained on the storage server for 7 days. If the diagnostic package has expired, then it can be re-created at %"

Hm… Let’s read the MOS: SPX86A-8002-XM – Memory Correctable ECC (Doc ID 1615285.1)

“Suggested Action for System Administrator

Replace the faulty memory DIMM at the earliest possible convenience.”

Hmm… But as I said, this was right after a maintenance on server, what if this is related?
Ok, some additional piece of information:

-> version 
SP firmware 3.2.9.23 
SP firmware build number: 116695 
SP firmware date: Thu Mar 30 11:38:01 CST 2017 
SP filesystem version: 0.2.10

At the current firmware level of SP firmware 3.2.9.23 the memory correctable error threshold limit for DIMM replacement is 240 CEs in a 72 hrs period.

So, the suggestion is:
– Clear all the error messages after complete the maintenance and lets check if the threshold is reached again. If so, we may need to really replace it.

How to do it? Easy:

ssh root@grepora01-ilom
-> show /SYS/MB/P0/D3
Expected:
[...]
fault_state = Faulted
[..]
-> set /SYS/MB/P0/D3 clear_fault_action=true
Are you sure you want to clear /SYS/MB/P0/D3 (y/n)? y
-> show /SYS/MB/P0/D3
[Expected]
 /SYS/MB/P0/D3
    Targets:
        PRSNT
        SERVICE
Properties:
type = DIMM
ipmi_name = MB/P0/D3
fru_name = 16384MB DDR4 SDRAM DIMM
fru_manufacturer = Samsung
fru_part_number = %
fru_rev_level = 01
fru_serial_number = %
 fault_state = OK
clear_fault_action = (none)

Hope it helps!
Cheers!

Database, GoldenGate

Oracle Streams: Adding a Table to Streams Replication

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Feel old yet?
Don’t worry, we all know that there are still companies using Streams. So, here goes a quick manual for a regular activity: Add a new table to replication using SYS.DBMS_STREAMS_ADM.

For this, assume the following:

STREAMS SETUP OWNER => streams_adm
CAPTURE PROCESS => str_capture
APPLY_PROCESS => str_apply
SOURCE DATABASE TABLE OWNER => TBLOWNER
TARGET DATABASE TABLE OWNER => TBLOWNER_DEST

The high level steps to add table to streams are as follows:

1. Stop streams CAPTURE
2. Create the table on the target database
3. Configure the CAPTURE process
4. Add a rule to the APPLY process
5. Instantiate the new object
6. Create constraints and indexes
7. Restart streams CAPTURE and APPLY

Let’s detail them:

More“Oracle Streams: Adding a Table to Streams Replication”