Oracle Direct NFS (and Linux Routing) … for Dummies!

When I started my current role a few months ago, I was very interested to learn that direction had been set to migrate away from ASM and onto NFS storage that had some read flash cache in front of it. I'm not the world's biggest fan of ASM and the (more...)

Tools that I use – nmap

For medium to large size projects the network setup can be quite complex, especially if it involves several external partners or third-party networks (VPN, MPLS etc).

Normally network changes are done by network engineers that do not have access to the servers and therefore cannot verify the changes they make.

When I have to verify a network change, firewall opening, NATing etc, I have in the past often used telnet.

This is very simple and (more...)

WebLogic Server and entropy

After input from Jacco H. Landlust and Edwin Biemond I have rewritten my post about entropy.


Entropy pool

In computing you often need random numbers. They are used for encrypting stuff but also for lots of other things.

For Linux servers random numbers are default provided by the /dev/random device. /dev/random is a pool of random bits (more...)

Bash script for installing WebLogic Server PSU patches via BSU

Patching WebLogic is necessary but not fun. To help out I have created a simple Bash script for installing CPU/PSU patches.

For information about CPU, PSU and SPU patches check this post.

The script is using BEA Smart Update so it is for WebLogic Server 12.1.1 and older. WebLogic Server 12.1.2 has switched from BSU to OPatch.

# ---------------------------------------------------------------------------
# Peter Lorenzen
# Version 0.9

IPython at Ohio LinuxFest 2013

Are you signed up yet for Ohio LinuxFest on Sep. 13-15? I'll be there to present

IPython for non-Pythonistas

Break out of your (bash) shell! IPython and the IPython Notebook have swept over the Python programming community, but they're not just for Python programmers - they make for high-powered shell (more...)

Configuring ODBC to MySQL from Oracle

Sometimes people want to connect to MySQL from Oracle and copy table data between the databases.  You can do that with Oracle Hetrogenous Services via ODBC.  This post will show how to create an odbc connection to your MySQL database which is the first part of this.

For my example, (more...)

oratop from MOS

This is just a pointer post to a tool which I discovered today. It is ORATOP, to monitor databases real time like top of unix flavours. It is pretty much like MOATS   (tool from Tanel Poder and Adrian Billington and RAC version by  Jagjeet Singh),   with a bit better output (more...)

Analyzing page allocation failures on Exadata

I have seen several clients who are struggling to decode page allocation failures on Exadata, in this post i will try to explain how to read the backtrace. The following is an anonymized client case where page allocation failures are leading up to a node reboot.

Jan 1 11:58:02 dm01db01  (more...)

Playing with VirtualBox, Oracle 12c ( and OEL 6.4 – Part 2

We will complete our lab by installing the Oracle Database software, create a Pluggable database and take a look in the Oracle Enterprise Manager Database Express.

The steps to install and create an Oracle Database 12c are:

1 – Go to the database directory created when unzipped the 2 Oracle (more...)

Playing with VirtualBox, Oracle 12c ( and OEL 6.4 – Part 2

We will complete our lab by installing the Oracle Database software, create a Pluggable database and take a look in the Oracle Enterprise Manager Database Express. The steps to install and create an Oracle Database 12c are: 1 – Go

Dual-Boot on UEFI PCs: Booting Ubuntu only works randomly

In my posting about using ubuntu on a Windows 9 laptop, i ended with:
But now rebooting works like expected (with Ubuntu and Windows 8).
After some more reboots and trying to start ubuntu, booting ubuntu only works randomly. Sometimes it worked after walking through BIOS/UEFI. Sometime it did (more...)

Linux and UEFI: Files, Mountpoints, Commands…

With Windows 8 secure boot is used. That means if you want to add a Linux kernel, this kernel has to be signed. After installing Ubuntu on a Windows 8 machine, here the directory listing of the /boot directory:
-rw-r--r-- 1 root root   844882 Okt  9  2012 abi-3.5.0-17-generic

Using Ubuntu on a Windows 8 Laptop: because of UEFI more problems as expected

Today i tried to install Ubuntu on a Windows 8 Laptop. First thing: you have to use 12.04 or greater because Windows 8 uses secure boot with UEFI.

But after the first boot with a USB-stick i got:

(initramfs) Unable to find a medium containing a live file system
?? (more...)

Linux Installfest, Dayton, Sat April 13

Dayton folks - are you coming to the Dayton Linux User Group's Installfest tomorrow?

The main point of our Installfests is to get everyone together for mutual help setting up and configuring computers and programs. But we like to throw in some educational talks, too, and I volunteered to give (more...)

Replacing JDK of JDeveloper on 64 bit Oracle Linux 6

As mentioned yesterday, I installed Oracle SOA/BPM Suite 11g PS6 yesterday. It was on Oracle Linux 6 Update 3 (still have to update to Update 4).

Today I installed the accompanying JDeveloper on the same machine. Everything went fine, except that apparently the installer failed to (more...)


Recently, I’ve been faced with a strange problem: around 10AM every morning, my database was showing signs of IO contention. Wait times for db file sequential and multipblock reads were increasing for no apparent reason and there were no signs of increased activity reported by the users. Fortunately, my system (more...)

Physical vs Logical Blocksize on ASMLib Devices

As you all may know, ASMLib is a recommended module for Oracle databases running on Linux platforms and it is an embedded module for UEK (Oracle Unbreakable Kernel) users. Oracle announced that (two years ago or so) they will no longer maintain ASMLib for Red Hat compatible kernel but this does not mean that they abandon the project, rather it is mainly related to the effort they need to put in maintaining the module for multiple kernel versions.

A while ago, Oracle added a new feature to ASMLib allowing ASM devices to choose between physical or logical block sizes in (more...)

Upgrade to Oracle Enterprise Linux 5.9 and/so UEK2

I have upgraded one of my Oracle Linux boxes to Oracle Linux Release 5.9 which introduces several new things (Release Notes). Just to mention three of them

Download and update yum repository file

[root@localhost yum.repos.d]$ cd /etc/yum.repos.d
[root@localhost yum.repos.d]$ wget
[root@localhost yum.repos.d]$ mv  (more...)

Protect your servers against brute force SSH attacks


I bet if any of you have an exposed server to an internet connection, without properly firewall protection, that your server is under heavy fire from hackers around the “world”… By the world I mean mostly China and Russia ssh attacks. If you’re curious, on Linux you can check the (more...)

Is your WebLogic Server slooow? Might be because of low entropy

On Linux low entropy can cause certain operations to be very slow.

SSL operations need entropy to ensure randomness. Entropy is generated by the OS when you use the keyboard, the mouse or the disk.

If an SSL operation is missing entropy it will wait until enough is generated.

If (more...)