Archive for November, 2009

can we change kernel parameter in linux when oracle is running

November 16th, 2009 No comments

I found the following question in my blog statistics:

“can we change kernel parameter in linux when oracle is running”

The answer is: Yes, of course!

You can alter any kernel parameter as long as it don’t require a reboot. If you set any kernel parameter to a lower value than your running database requires there wont be any impact in time – but there might be problems when your database continues to run (e.g. unable to start new sessions, degraded performance).Once your database is shut down and you lowered for instance the SHMMAX parameter you wont be able to start the instance.

Therefore you should make sure to increase the values and check twice!

Categories: Oracle in general Tags:

Authentificate Oracle user passwords against Active Directory using Radius

November 16th, 2009 No comments

I developed this topic last year while taking the OCP course. The instructor told us about oracle authentication and because i was a little bit bored i played around with it. My goal was to use oracle external authentication to authenticate against a radius server which authenticates against an active directly (or any other LDAP server).

With this technology you can implement a centralized password and account management quite easily although users still have to be created in the database and they still have to be granted roles and permission to them in the database. Active Directory (i will use this term in the whole article…. as said instead of active directory use can use another other LDAP server as well) is solely used to:

  • verify the users password
  • check the account state and grant access only if the account is not locked

For using this authentication mechanism the “Oracle Advanced Security Option” is needed.

Read more…

Categories: Oracle in general Tags:

Metalink HTML (aka. “non-flash”) Interface

November 12th, 2009 No comments

Classic Metalink retired the last weekend. New flash-bashed Metalink currently faces a lot of problems (to be honest: it is at the moment [12th November 2009] completely unusable). Beside this major errors there are other problems: such as incredible high cpu demand (on my system flash player takes 100% CPU accessing metalink).

If you´re looking for a non-flash alternative there is an HTML metalink interface available. You can find it here: At themoment the HTML portal is extremely slow and unstable….. but for companies which do not allow flash to be installed at all the only solution.

Categories: Oracle in general Tags:

I am now an OCE (Managing Oracle on Linux Certified Expert)

November 11th, 2009 3 comments


As of today i successfully passed the exam to become an OCE. Next certifiecation i am working on is “Oracle Database 10g: Real Application Clusters Administrator Certified Expert”.

Categories: Oracle in general Tags:

Logging syslog and database audit messages to an oracle database with rsyslog

November 11th, 2009 14 comments

A few months ago i tested yet another syslog implementation: rsyslog. Among all other available syslog implementation such as syslog or syslog-ng rsyslog offers some nice features such as:

  • database support
    • MySQL
    • Postgres
    • Oracle
  • Failover log destinations
  • syslog over tcp
  • fine grain output format control
  • high precision timestamps
  • filer on any message part
  • compatible with syslog
  • encryption support

So i took the oracle module for rsyslog and tried to get it working. A documentation did not relly exists so i wrote one which is part of the module now. Recently i took a look at rsyslogd again and did some test with rsyslog – especially how to store syslog messages and log oracle audit messages in a queryable way in an oracle database. My experiences will be covered in this article.

Disclaimer: All scripts, packages, procedures are released under the GPL. You can use them freely but on your own risk. However i would like you to send me the changes you made so i can perhaps improve the components.

Read more…

Categories: Oracle in general Tags:

Oracle 11g 2 Release for Solaris SPARC available

November 9th, 2009 No comments

As of today (09th November 2009) Oracle 11g Release 2 is available for Solaris SPARC.

You can download it from OTN.

The release includes database, client and grid infrastructure (aka “clusterware” as well).

According to the release schedule Oracle 11g Release 2 for Solaris INTEL is most likely to be released next. Windows is scheduled for the second quarter in 2010. See my previous post for more information about possible release dates.

Categories: Oracle in general Tags:

Building a custom and cheap storage server yourself

November 6th, 2009 No comments

Recently i came across a project where they built their own cheap storage. The whole story is documented here and here.

A colleague of me and i saw this project and wondered if this kind of storage could be used for databases as well. So we analyzed the design and noticed some problems from our point of view:

  • data access only via HTTP
  • they used the JFS file system which is not widely used
  • generally hard disks are hot-swappable; but not used due to fear of problems
  • optimized for space rather than for speed
  • relatively “weak” power supply

So we tried to improve the layout with the following constraints:

  • approx. 10.000 Euro (approx. 15.000 US-Dollar) in total
  • Storage accessible via multiple protocols:
    • NFS
    • iSCSI
    • NFS
    • CIFS
    • if possible SAN
  • Reliable
  • Optimized for speed rather than capacity (remember: we talked about databases)
  • Hot-Swapable Harddisks

This is part I of our journey towards building a storage system ourself. Part II is here and Part III here.

Read more…

Categories: Openstorage Tags:

Which file system to choose for running Oracle on Linux

November 5th, 2009 2 comments

Beneath the battle of the operating systems (Windows vs.UNIX) there one argumentation after deciding for running oracle on Linux: The choice of the file system and the “correct” partition layout.

This article will sum up what file system are certified for running oracle on Linux (and other platforms as well) and will especially discuss the available file systems on Linux. My opinion regarding an optimal partition layout is written here.

Recommendations regarding the partition layout can be found in an older post here.

Read more…

Categories: Oracle in general Tags:

Oracle 11g Release 2 – RMAN compression comparison

November 4th, 2009 15 comments

Starting with Oracle 11g Oracle added several compression algorithms to compress data. They can be used for compressing tables, LOBs , compressed data pump exports or even RMAN backups. Unfortunately for some compression algorithms you need to purchase the “Advanced Compression Option”. The following table lists the available RMAN compression options, the most likely compression algorithm being used and states if an additional license is required:

RMAN Compression TypeCompression Algorithm usedAdv. Compression License required?Backup set sizeCPU Load
BASICBZIP2 (100k record size?)Nosmallmedium to high
NONEnoneNolargest; approx. db sizeextremely small
LOWLZOYESsomewhat smaller than using NONElow
HIGHBZIP2 (900k record size?)YESsmallesthighest

This article is intended to take a look at the different compression methods available in Oracle 11g and to compare them.

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ACFS Snapshots

November 3rd, 2009 1 comment

This is a short article about ACFS and the acfs snapshots feature – a new 11g Release 2 feature: How to create, work with and drop a snapshot.

ACFS is the ASM Cluster File System and ships with Oracle 11g Release 2. For using ACFS first of all an ADVM volume must be created and an ACFS file system created on top of it. The same ACFS file system is available on all nodes in the cluster. The data itself is stored in an ASM disk group. More information can be found here. The documentation is available here and here.

Read more…

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