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Ubuntu: install vmware-server 150 150 Roderick Derks

Ubuntu: install vmware-server

A good idea if you'd stil like to have a stupid Windows os on your system cause the application you'd like to is not available for Linux: use vmware-server. read more

Ubuntu: wireless network with wpa encryption 150 150 Roderick Derks

Ubuntu: wireless network with wpa encryption

Yo, this is the way to connect your Wonderfull Wireless Ubuntu Wanker (laptop) to the network. What I used is an Intel Pro Wireless card and Ubuntu 7.04 linux distribution. It's got a real fancy desktop and it consumes much less memory than Windows Vista, you'll be amazed.. read more

Fedora: online disabling of SELinux 150 150 Roderick Derks

Fedora: online disabling of SELinux

Fedora ships with SELinux (Security Enhanced Linux) installed and in Enforcing mode by default. This can result in "Internal Server Error" messages when you attempt to access or install software.

See if SELinux is in Enforcing mode.

# getenforce

Put SELinux into Permissive mode.

# setenforce 0

The Nagios CGIs should work now. To make this change permanent, you'll have to modify /etc/selinux/config.

VMware guest OS on dual-display monitor 150 150 Roderick Derks

VMware guest OS on dual-display monitor

What?
Linux workstation with dual LCD monitors at 1920×1200 resolution on each screen. Need to have a single virtual Windows machine running on both monitors at full screen.

How?
1. Set-up Linux to use both monitors as single display using Twinview.
2. Install VMware Workstation. My installation version was 5.5.3 build-34685.
3. Install the virtual Windows machine.
4. Install VMWare Tool from the virtual Windows machine. Make sure VMware Tool is running.
5. Edit the virtual machine config, *.vmx file.
svga.maxwidth = “3840″
svga.maxheight = “1200″
svga.vramSize = “134217728″

Notes
* Width is 3840 because width of dual monitors, 1920+1920=3840.
* Default virtual graphic card ram size is 16MB. This is not enough to get the full 3840×1200 display. Need to adjust to higher value hence 134217728 @ 128MB.

Resize linux partitions (physical and virtual using VMware) 150 150 Roderick Derks

Resize linux partitions (physical and virtual using VMware)

The reason why I wanted to change the sizes of the partitions of one of my linux systems was the lack of space on the root partition. I'm running this linux system as a Virtual Machine (VM) using 256MB of RAM.

I could have choosen to enlarge the vmdk file (the virtual disk), but I didn't. I'll tell you why. In a VM you can have a swap partition of half the size of the amount of memory (VMware recommendation). As I sticked to the 'linux-out-of-the-box-installation' 512MB was used for the swap partition. So I decided to shrink the swap and use it to extend the root partition.

System used: Fedora Core 6 (but the procedure does not only apply to this linux flavour) and VMware server, though the latter is not quite relevant in this situation.

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Nagios: howto become a happy network and system monitoring engineer 150 150 Roderick Derks

Nagios: howto become a happy network and system monitoring engineer

I’m giving Nagios a try, a very interesting Network Monitor system. It’s pretty cool stuff, but you have to take the time to get to know it. The setup and especially the configuration can get complicated.

The Nagios community is pretty lively and there are a lot of plugins you can download and use. The good thing is that there are a lot possible strategies on how to monitor you network. So, you just have to experiment and find out what you want, where to get it, how to install it and how to set it up. And when you’re finished, boy do you deserve a nice cool glass of beer. Better, do not wait drinking a beer ’till you’re finished, you’ll need it much earlier.

Article status: work in progress, last edit: januari 6, 2008

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How to use snmp on your network 150 150 Roderick Derks

How to use snmp on your network

For a snmp server I used a vmware virtual appliance: cacti.
The clients I configured up till now are Fedora Core 6 environments. Windows will be added later on. read more

How to handle .tar.bz2 files 150 150 Roderick Derks

How to handle .tar.bz2 files

Files with the extension .tar.bz2 are compressed tarballs, a common way of sharing files on the internet. The compression rate is higher then that of a *.tar.gz or *.tgz file. Unpackig demands more CPU though.

You can extract files from a tarball using the ‘tar’ command, this will creat a new folder containing the files from the tarball.
# tar xvjf bestand.tar.bz2

Create a tar archive
# tar cvjf name_of_your_archive.tar.bz2 /path/to/directory

short explanation:
-x : extract
-c : create
-v : verbose
-j : type of compresssion used: bz2
-z: type of compresssion used: zip (*.tar.gz files)
-f : filename

scripts

A way to tar and zip files simultaniously using a script:

tar cvf –  ./apl       | gzip > /backup_dir/apl.tar.gz           &

tar cvf –  ./bin       | gzip > /backup_dir/abin.tar.gz          &

tar cvf –  ./dualpath  | gzip > /backup_dir/adualpath.tar.gz     &

 

Tuning Journaling File Systems 150 150 Roderick Derks

Tuning Journaling File Systems

File systems are part of our everyday lives. We store and retrieve data constantly, but rarely do we think think about how each file system works. Perhaps that’s as it should be: Linux supports many different kinds of file systems, and most are mature and robust. For example, the Linux kernel supports the traditional Ext2 file system (among others), several cluster file systems (Lustre, GFS, GPFS, and CXFS), and also includes no less than four journaling file systems that have been proven time and again in production server environments, where high throughput and near-perennial uptime is essential. (For additional information on journaling file systems, see the October 2002 Linux Magazine article titled “Journaling File Systems”, available online at http://www.linux-mag.com/2002-10/jfs_01.html.)

But journaling file systems need not be limited to servers. Journaling file systems can also benefit client machines, where performance and reliability is often just as critical. However, the jobs assigned to a workstation and the demands placed on a server are radically different. To get the best high throughput and high uptime requirements performance out of both, you have to tune each configuration to suit. Let’s use the open source dbench benchmark (http://samba.org/ftp/tridge/dbench/) to tweak and measure a number of different workloads and see how a little work can yield big results.

(This article taken from the www.linux-mag.com website, author Steve Best)

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Journaling File Systems 150 150 Roderick Derks

Journaling File Systems

The file system is one of the most important parts of an operating system. The file system stores and manages user data on disk drives, and ensures that what's read from storage is identical to what was originally written. In addition to storing user data in files, the file system also creates and manages information about files and about itself. Besides guaranteeing the integrity of all that data, file systems are also expected to be extremely reliable and have very good performance.

For the past several years, Ext2 has been the de facto file system for most Linux machines. It's robust, reliable, and suitable for most deployments. However, as Linux displaces Unix and other operating systems in more and more large server and computing environments, Ext2 is being pushed to its limits. In fact, many now common requirements — large hard-disk partitions, quick recovery from crashes, high-performance I/O, and the need to store thousands and thousands of files representing terabytes of data — exceed the abilities of Ext2.

Fortunately, a number of other Linux file systems take up where Ext2 leaves off. Indeed, Linux now offers four alternatives to Ext2: Ext3, ReiserFS, XFS, and JFS. In addition to meeting some or all of the requirements listed above, each of these alternative file systems also supports journaling, a feature certainly demanded by enterprises, but beneficial to anyone running Linux. A journaling file system can simplify restarts, reduce fragmentation, and accelerate I/O. Better yet, journaling file systems make fscks a thing of the past.

If you maintain a system of fair complexity or require high-availability, you should seriously consider a journaling file system. Let's find out how journaling file systems work, look at the four journaling file systems available for Linux, and walk through the steps of installing one of the newer systems, JFS. Switching to a journaling file system is easier than you might think, and once you switch — well, you'll be glad you did.

(This article taken from the www.linux-mag.com website, author Steve Best)

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