Linux LVM How-to: Adding a new partition

Since I started out with Linux (so about six years ago), I always used the Linux Logical Volume Manager (LVM) to partition my tables. First it was just because it seemed easier to configure my harddisks with it (also, the installer usually provided a nice option to do so), but in the last few months I had the possibility to work more with LVM and got to know some nice features.

One thing I regularly have to do is to extend an existing logical volume on a server. This article focuses on extending a logical volume with the help of LVM.
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Mac OS X: Plotting with GNU Octave (libfreetype)

For our courses in linear algebra, we are using the GNU Octave software for numerical computation. Since I am using a MacBook Air for university, I had to install Octave on Mac OS X. I simply followed the steps described here and successfully installed gnuplot and the Octave software package. But when I tried to plot something with Octave, I received the following error message:

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Nagios: Escape dollar character

Some services (such as MSSQL instances) include a dollar character ($) in their name. A few weeks ago, I had to add a service called “$02_JBoss Server” to our internal Nagios configuration. After searching through the Nagios documentation and FAQs, this is what I found:

For Nagios 3, add two backslashes and a second dollar (\$) symbol, like this: check_command check_command check_nt!SERVICESTATE!-d SHOWALL -l MSSQL\$$INSTANCE

The above example actually has a small error in it, because there is no second backslash (even though it says so in the description)!

The correct way to check a service named “$02_JBoss Server” is to use a definition like this:

check_command           check_nrpe_args!CheckServiceState!ShowAll "\\$$02_JBoss Server"

Nagios: Check iSCSI Initiator

In the last few weeks I reworked our internal Nagios configuration and added a few checks to some of our internal servers. Since we do not have a dedicated SAN for our environment, we are using iSCSI as a low-cost storage solution. However, the Microsoft iSCSI Initiator implementation sometimes has trouble connecting to the iSCSI target. As a result, we had to monitor the iSCSI Initiator.

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