Simon Krenger

To monitor our software, we use the free Nagios supervision system fitted with custom checks for our application. This way, we can make sure that not only the Operating System is properly monitored but also the core components of our application including the Application Server and the Oracle Databases.

Today I tried to update to the latest version of Nagios 3.3.1 on one of our supervision servers running Ubuntu Server. So I downloaded the package, ran “./configure” and ran “make fullinstall“. I then stumbled upon the following (quite meaningless) error:

/usr/bin/install: omitting directory `includes/rss/extlib'
/usr/bin/install: omitting directory `includes/rss/htdocs'
/usr/bin/install: omitting directory `includes/rss/scripts'
make[1]: *** [install] Error 1
make[1]: Leaving directory `/tmp/nagios-3.3.1/nagios/html'
make: *** [install] Error 2
root@watchtower:/tmp/nagios-3.3.1/nagios#

Phew. Alright, using my trusty friend Google I quickly discovered a thread on ubuntuforums.org with the solution.

When deploying a new database, one thing I usually do is to set up a logrotate configuration for the Oracle Listener log. The Oracle Listener logs every connection he makes and when using an Application Server to interface the database, this file can grow quite a bit. So we need to make sure that we properly rotate this log and compress the old logs.

To achieve this, I usually create the following configuration for logrotate:

I just noticed that every time I need to create a password file, I have to look up the Oracle documentation for the correct syntax of the ORAPWD arguments. So this post is mainly for my own reference and contains the proper syntax for UNIX and Windows systems as well as an example for each system.

UNIX syntax:

In the last weeks, I have been considering to replace my HostEurope vServer (Linux L 4.0) with an Amazon EC2 Micro Instance. I already did some testing in another post and then stumbled upon a post mentioning CPU stealing. So I did some testing myself…

The Linux kernel provides the tmpfs, which basically creates a file system in memory. This temporary file system can be used to store temporary data, such as caches or log files. Read more about tmpfs in the kernel documentation: tmpfs.txt

After reading this excellent article about using tmpfs in Linux, I decided to put it to the test. Even though the Linux kernel already does a good job caching files, I wanted to see the performance of this solution by applying different loads on it. For this, I am using the IOzone tool I already used for my ZFS tests (1) (2) and my Amazon EC2 IO test.

So one might want to ask why you’d want to sacrifice the fantastic stability and openness of Debian to install a vanilla (= original) kernel (Debian currently has 2.6.32). There are quite a few reasons for doing so. For example, the current kernel (2.6.38) has TRIM support, which is something I am looking for when using SSDs. Also, maybe you want to have a bleeding edge kernel just for the fun of it. So lets get started.

First order of business is to download a few packages, download the latest kernel from kernel.org and then unpack the kernel in /usr/src/:

While discussing the topic of cloud computing today, my co-worker mentioned the Amazon EC2 service and gave me a quick presentation of the features that are available. Since I am a big fan of virtualisation and the idea of scalable architectures, I immediately thought “This could be great to test some things out and is a wonderful opportunity to play around with different virtual machines”. So I signed up and did some quick tests to look at the IO performance…

I was especially interested in using these machines for storage and maybe some tests with databases. For these tests, my current Virtual Server serves as a reference, simply because EC2 could provide an alternative to that Virtual Server. In my tests, I included the following configurations:

One of the first things I do when I install PuTTY on a new machine, is to change the default color settings to something that is easier to read. This is a problem I have noticed on Red Hat machines, where the terminal color settings are not that great.

When you do an “ls” for example and the output contains folders, these are shown in a dark blue color, which makes it very hard to read on a black background. See the first picture in the gallery below.

Using Red Hat with Samba (Version 3.0.10-1.4E.11), I had the problem that Windows Explorer would not refresh properly when browsing the folders served by Samba. When creating a new folder, nothing showed up and it was necessary to manually refresh the Explorer window to see the “New Folder”. The same symptoms appeared with newly created files.

To fix this, add the following line to the [global] section of your smb.conf (usually located under /etc/samba/smb.conf):

[global]
refresh = 1

Sadly, I could not find this parameter in the official Samba manpages. Should anyone have more information or any documentation on this, feel free to let me know.

When I was installing Red Hat Enterprise Linux on a server, the machine suddenly hung at the following line:

PCI: Probing PCI Hardware (Bus 00)

This is a well-known problem (as a simple search on Google will reveal), so to solve it simply add the following parameter to the kernel boot configuration: