Super-Sizing PGA Workareas in Oracle 12c

After a customer asked me for possibilities of super-sizing PGA workareas in version 12c, I took the chance to revisit the topic and perform some tests. Great material has already been posted by Alex Fatkulin (Hotsos Symposium 2014) and Norbert Debes (Secrets of the Oracle Database, Apress), but I wanted to verify, how the current release is behaving and I found some interesting things.

Super-Sizing PGA Workareas in 12c

Cloud Control – Privilege Delegation – so you don´t have the oracle / root password?

Quite frequently in database environments, security policies dictate that only personalized logons to Unix / Linux are allowed and that from there, one has to “sudo” to change to the oracle account. While this adds an additional layer of security, it makes administration a little more complicated.

Oracle Enterprise Manager – Cloud Control has a feature, which allows to cope with such a sudo environment. The feature is called “Privilege Delegation”. This post describes how (more...)

ORA-4031 Troubleshooting – Issue with durations in 11gR2

I recently had to troubleshoot an ORA-4031 issue at a client site. The issue reappeared 3 times within 2 months and only after escalating the SR to SEV1 and being quite persistent for an explanation, the second engineer attempting to solve the issue finally got it right.  Being curious, I digged into the trace files again to confirm and understand the issue here. This blog post describes the method to analyze the issue and (more...)

Oracle Database Result Cache Troubleshooting

I was troubleshooting an issue where the Oracle Database Result Cache did not get used when the RESULT_CACHE hint was specified inside a subquery. As the main query has a sysdate inside, the RESULT_CACHE Hint can not be specified for the main query, but only for the subquery.

1
2
SELECT SQ.*, sysdate FROM
(SELECT * FROM tableX, ....) SQ;

When using “/*+ RESULT_CACHE */ inside of Subquery, result cache was not (more...)

Oracle Linux Update from 7.2 to 7.3 crashes with uncorrectable CPU error

During the Upgrade of Oracle Linux 7.2 to 7.3 with “yum update”, when updating the microcode_ctl package, the system crashed and firmware reported an uncorrectable CPU error after reboot.

It turned out that the update of the package in combination with specific Intel CPUs causes the issue. In the meantime, there is a red hat bug and solution available.

 

References:

  • https://community.oracle.com/thread/3997160
  • https://bugzilla.redhat.com/show_bug.cgi?id=1398698
  • MOS: The system could (more...)

Problems with big SGAs (>200G) on Linux

I recently had an issue where a database with 240GB SGA (1 huge shared memory segment) configured with hugepages on a system with 512G RAM was suddenly becoming instable and new logons were denied with these error message:


ORA-01034: ORACLE not available
ORA-27123: unable to attach to shared memory segment
Linux-x86_64 Error: 22: Invalid argument
Additional information: 2667
Additional information: 1736718
Additional information: 215016800256

This was strange because ipcs -a showed all shared memory segments (more...)

EM 13c: Do not change OPatch

In previous versions, it was “best practice” to always get the most current opatch (patch 6880880) from MOS. Unfortunately, with Enterprise Manager Cloud Control 13c, this is problematic at the moment. The reason is that OMS 13.1 is shipped with OPatch 13.6:

[oracle@em13c ~]$ opatch version
OPatch Version: 13.6.0.0.0
 
OPatch succeeded.

Currently, OPatch 13.6 is not available in MOS. Only OUI Nextgen (more...)

EM12c: opatchauto failed with error code 231

When trying to patch OMS 12.1.0.5 in a VirtualBox environment with latest OMS PSU, I came across a strange problem which took quite a while to solve. The opatchauto apply and also -analyze commands failed every time with this error after several minutes of hanging:

opatchauto failed with error code 231

Manual connect to WLS console with relevant protocol/host/port/username/password was working fine. Then I realized that there was an issue with the (more...)

AWR Warehouse – security issue

During implementation of AWR Warehouse, I discovered that AWR warehouse is using temporary staging schemas in the AWR warehouse repository database. These schemas life approximately for the duration of a datapump import job and are then dropped again. Due to the fact that the used password is not compliant with customers password verification function, the jobs failed.

v_sql := ‘ CREATE USER ‘ || STAGING_SCHEMA || ‘ IDENTIFIED BY SYS_GUID ‘ ||
‘ DEFAULT TABLESPACE (more...)

OPatch bugs when applying Grid Infrastructure 12.1.0.2.5

For one of my clients, I experienced several issues with applying PSU 12.1.0.2.5 with opatch 12.1.0.1.9.

There were some code changes in opatchauto, which are not yet production-ready. I am looking forward to seeing a new opatch release (maybe 12.1.1.10 or 11) which has these issues fixed.

  • Bug 22091017 : OPATCHAUTO -ANALYZE COMMAND SHUTS DOWN THE RDBMS HOME IN 12C
    “opatchauto apply -analyze” is (more...)

Clobbering grub.conf is Bad

I’m sharing this in the hope of saving someone from an unwelcome surprise.

Background

I recent upgraded an Exadata system from 11.2.3.2.1 to 11.2.3.3.1. Apart from what turns out to be a known bug[1] that resulted in the patching of the InfiniBand switches “failing”, it all seemed to go without a snag. That’s until I decided to do some node failure testing…

Having forced a node (more...)

Changes in Oracle Linux 7

The following is a list of changes I noted during installation of Oracle Linux 7. I imagine the same will apply to Red Hat Enterprise Linux 7, but I haven’t verified that to be the case.

Setting the Hostname

I was accustomed to updating /etc/sysconfig/network with the hostname of my machine as documented here for Oracle Linux 7. I did this and was then surprised to find that my hostname was not picked up. On returning (more...)

Define Your Own Role for Database Target Access in EM12c

Scenario

  1. Enterprise Manager 12c (EM) installed and agents rolled out to database servers
  2. Access to EM offered to development teams with the primary purpose of allowing them to investigate application related database performance issues

Documentation

The EM documentation covers a selection of privileges you might want to grant to users in database targets in order to allow them to be used for accessing EM functionality. The privileges mentioned are:

  1. SELECT ANY DICTIONARY
  2. CREATE SESSION
  3. EXECUTE on (more...)

Internet Access with VirtualBox & Host-only Networks (on OS X Mavericks)

Introduction

When creating VMs on my laptop I like to configure the minimum number network interfaces. I also tend to end up with environments where I want multiple VMs to be able to see each other, see the internet and see my physical host. It seems many people using VirtualBox use the approach of having a “Host-only Adapter” interface and a “NAT” interface. The only reason I have for not liking this is that it (more...)

Kdump to NFS in UEK (Solution)

I’ve previously written about a problem I encountered when kdump is configured to write to an NFS location with UEK (in Exadata software version 11.2.3.2.1). I’m please to report that the root cause of the problem has been identified and there is a very simple workaround.

There were some frustrating times working this particular SR, the most notable being a response that was effectively, “It works for me (and so I’ll (more...)

Hidden Perils of Thin-style Service Name Syntax with UCP & FCF

I’ve touched on this issue before over at my previous blog and also talked about it at UKOUG Tech13. The presentation at Tech13 was more than 90% demos so hasn’t left a lasting record of the issue and the previous blog post doesn’t go into significant detail. I think it (more...)

12c Improvement in Database Service Management

Removing a service via srvctl has not historically resulted in the service being fully removed from the database and it would still be visible in DBA_SERVICES as show below in an 11.2.0.3 database:

Create the service:

$ srvctl add service -d orcl -s demo -r "ORCL1,ORCL2"

Have (more...)

Kdump to NFS Broken in UEK

There were problems that affected UEK and NFS when 11.2.3.2.1 was initially released (as covered by Andy Colvin). As mentioned in the comments of Andy’s post: Oracle released an updated ISO with fixes for this problem (patch 16432033).

There were also problems with kdump not (more...)

Sudo Keystoke Optimisation

If like me, and a couple of others I’ve spoken to recently, you were not previously aware of “sudo -s” then you might be interested to know that you can save yourself two keystokes by switching from:

sudo su -

To:

sudo -s

From the man page:

The -s (shell) (more...)