Oracle Disaster Recovery with Microsoft Hyper-V Replica

There is one very interesting feature of Microsoft Hyper-V called Replica, which allows replication of Virtual Machines without shared storage. With Hyper-V Replica, one can set up Oracle Database VMs to replicate between independent nodes. This document (in german) describes the setup in more detail:

Hyper-V Replica für Oracle Database

Enterprise User Security – Presentation Material available

On the presentations page you can find the my presentation material from DOAG regional meeting September 2014 in Munich about “Enterprise User Security”.

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...)

11.2.0.4 DBUA silently changing NLS_TERRITORY init.ora Parameter during upgrade

In case you are planning to perform any upgrades with DBUA, double-check that the init.ora parameters after the upgrade. In a production upgrade at a client site, dbua silently changed init.ora parameter NLS_TERRITORY from GERMANY to AMERICA. It was only noticed when after the upgrade, decimal and grouping number characters were swapped, leading to application problem.

Support had to admit that it is unpublished bug 16538186 and that there is NO documentation of (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...)

Index Clustering Factor finally more realistic

I just stumbled upon this bug reference on My Oracle Support:

Bug 13262857  Enh: provide some control over DBMS_STATS index clustering factor computation

This enhancement was long due. Previously, when computing the clustering factor during gathering statistics, the value was incremented, whenever the row was not found in the same block as the previous row. Now, it is finally possible to determine how many blocks should be considered when computing clustering factor. The patch delivers an improved DBMS_STATS package body that can be used to set preferences with value TABLE_CACHED_BLOCKS.

The flaw in the over-simplistic and pessimistic original computation was (more...)

Datapump Export suffering from Oracle Row Migration

Recently, i was troubleshooting a datapump export duration problem. Over the period of 18 months, the duration of a multi-table export increased dramatically. A quick analysis showed that the export duration was mainly dependent on one big table. This 50 GB table with no BLOB/CLOB/LONG datatypes took more than 4 hours on a modern system wheras it should not take more than 10 – 15 minutes. The system was performing ONLY single-block I/O requests (db file sequential read). I found this strange and started investigating.

Beginning with 11g, you can enable sql_trace (10046) for datapump with the new syntax:

ALTER  (more...)

Bug 13397104: INSTANCE CRASH WITH ORA-600 [KJBLPKEYDRMQSCCHK:PKEY]

I would like to point your attention to a bug in RAC 11.2.0.3. The bug leads to instance crashes during Dynamic Remastering. As of June 1st, there is no patch publicly available. The workaround seems to be to set:

_gc_read_mostly_locking=false

So, if you are thinking about upgrading your RAC to 11.2.0.3, maybe you should wait just a little bit longer… ;-)

More details are in MOS: Bug 13397104: INSTANCE CRASH WITH ORA-600 [KJBLPKEYDRMQSCCHK:PKEY]

Update 12.06.2012: Patch 13397104 is now available in MOS for 11.2.0.3.

Oracle certifies OEL6/RHEL6 for Oracle Database 11gR2 and Fusion Middleware

Oracle yesterday announced certification of RHEL6 / OEL6 with Oracle Database 11gR2 and Oracle Fusion Middleware 11.1.

Moreover, Oracle will from now on provide errata packages for free. Until now, they could only be obtained with a valid ULN support contract. I think this will be a big plus for Oracle Linux in competition with Red Hat Enterprise Linux.

I wonder how long it will take before they ship Exadata and Oracle Database Appliance (ODA) with Unbreakable Kernel.

Reference: http://www.oracle.com/us/corporate/press/1563775

No more cleartext-passwords in Scripts – Oracle Secure External Password Store (SEPS)

Gone are the day when cleartext passwords had to be stored in scripts for Oracle database access. The solution to this requirement is “Oracle Secure External Password Store (SEPS)”. This article will give a short introduction and a practical example of the solution.

Key facts:

  • no Advanced Security Option (License) necessary
  • every unix-account, who has access to the wallet can use it to log on to the contained databases without a password! Therefore prevent other unix-accounts from accessing your wallet! (chmod, chown)

Installation

  • Oracle Client: Unix-Account, who wishes to connect to the database without providing a password needs to (more...)

Bug: ORA-4031 for subheap “KTC latch subh” in 11.2.0.3

I just saw MOS Note

ORA-4031 After Upgrade From 11.2.0.1 To 11.2.0.3 With Leak in ‘KTC latch subh’ Subheaps [ID 1398984.1]

giving very little information about this bug. At the time of this writing, there is no patch available but I expect it to be in a few days. I have checked some 11.2.0.3 instances and found only one with > 60 MB for this subheap.

Oracle SCN Problem

In case you have not heard all the buzz about the Oracle SCN flaw, which was published by Infoworld after the release of January CPU, I summarize the essentials.

  • There is a risk that the SCN reaches it´s maximum value and this could lead to an outage of the database.
  • There is a bug in “ALTER DATABASE BEGIN BACKUP”, which increases the SCN dramatically. (Bug 12371955 – fixed in 11.2.0.2.4 and others)
  • When you query a remote database via database link from a database with elevated SCN, the remote SCN gets increased to the higher value (more...)