When it comes to virtualization, there are a few platform arenas to consider: 1. the server, 2. the virtual desktop, and 3. the cloud. It appeared for some time that IBM was satisfied relying on VMware for its virtualization needs, but they have recently announced that they will use Red Hat’s technology for their cloud for developers virtualization.

The business world is already filling up with cloud computing offerings for productivity (email, calendar systems, etc - think Google), and advanced remote storage (think Amazon), but IBM is tapping into an apparent opening for cloud-based software development. Developers will be able to develop and test applications in the cloud.

Red Hat, famous for its early hugely popular Redhat Linux, continues to make strides in the enterprise market with its Redhat Enterprise Linux and now with its virtualization technology. IBM does not anticipate an overnight success but intends to build a substantial increase over time. Although cloud computing enters the news frequently, it still only counts for a fraction of all web hosting with many businesses still preferring locally hosted solutions.

Source: ServerWatch

Continue reading: IBM chooses Red Hat for its cloud virtualization

OpenVZ is a free and open source virtualization solution for Linux. Here is an easy guide to installing OpenVZ on Redhat Enterprise Linux, CentOS, or Fedora.

Note: It is recommended that you use an ext2 or ext3 file system if you want per-container disk quota.

1. Add the OpenVZ YUM repository:

# cd /etc/yum.repos.d
# wget http://download.openvz.org/openvz.repo
# rpm --import http://download.openvz.org/RPM-GPG-Key-OpenVZ

2. Find out which kernel version you need and install it:

# yum install ovzkernel[-flavor]

3. Change the new GRUB bootloader lines created when you installed the kernel to look something like this in /boot/grub/grub.conf:

title OpenVZ (2.6.8-022stab029.1)
root (hd0,0)
kernel /vmlinuz-2.6.8-022stab029.1 ro root=/dev/sda5
initrd /initrd-2.6.8-022stab029.1.img

That’s it! You now have OpenVZ installed. Visit the OpenVZ wiki for more information about configuring your new installation.

Source: OpenVZ Quick Installation

Continue reading: How to install OpenVZ with yum

Nginx (pronounced “Engine X”) is a lightweight web server that offers speed and flexibility without all of the extra features that larger web servers like Apache offer. Although it is a free and open source application, CentOS does not offer the latest version in its default YUM repository. To install it, you need to add the EPEL (Extra Packages for Enterprise Linux) repository, which is part of the Fedora Project.

1. Install the EPEL repository:

# rpm -Uvh http://download.fedora.redhat.com/pub/epel/5Server/x86_64/epel-release-5-3.noarch.rpm

2. Install nginx

# yum install nginx

3. You will be asked to install the gpg-key for EPEL. Answer yes

4. Start Nginx

# /etc/init.d/nginx start

5. Check the installation by going to your web server’s default site, either using your ip address or domain name.

Continue reading: How to install Nginx via YUM in CentOS

Question: Two of my directories on my server have some the same files. How can I easily delete any duplicates while preserving the unique files?

Answer: There exists a Linux tool for just about everything, and this is no exception. You need a tool called fdupes, which searches the path you give it for duplicate files and uses several comparison techniques (sizes, MD5 signatures, byte-by-byte comparison) to find and eliminate duplicates.

First install fdupes. In RHEL/Fedora/CentOS, use the rpmforge repository enter:

# yum install fdupes

To find duplicates in the /etc directory, you would enter:

# fdupes /etc

To force fdupes to prompt you whether to preserve or delete files:

#fdupes -d /etc

As you can see, fdupes might be just what you need to clean up your server and possibly increase that precious disk space.

Source: nixCraft
Photo: Wikimedia Commons

Continue reading: How to delete duplicate files in Linux

Over the past year, we have discussed many different schemes for Linux servers, which included many Linux distributions. Here is a quick overview of the major players in the Linux server market.

Redhat Enterprise Linux - With the biggest financial revenue in the Linux market, Redhat is a force to be reckoned with, but whether they are right for your web hosting company depends on how much you can afford. If you like Redhat, you might consider CentOS.

CentOS - A free alternative to RHEL, based on the same source code, minus Redhat’s guarantees, technical support, and logo artwork.

Fedora - The cutting-edge testbed for RHEL. This is a community driven OS with a lot of community support but not paid technical support.

Continue reading: Linux server round-up

Question: Which Linux services should be enabled at boot on a server?

Answer: Most Linux distributions come with more than what you need. They are designed to not only work on servers but also desktop computers, laptops, netbooks, and in some cases, even smaller mobile devices like phones. Because of this there are sometimes numerous services running that you may not need. Similarly, there might be special server-oriented services that you will want to enable.

Security is also an issue. In the past we covered X.org and why it is a bad idea to have it running on a server. There are other services like X.org that might be good for the desktop but are superfluous on a server. The first thing to do is to find out which services are currently running. Execute the following commands:

#service --status-all
#chkconfig --list | grep '3:on'

You can read the rest of the steps in tis process at nixCraft. Everything in the complete how-to article will cover CentOS, Fedora, and Redhat Enterprise Linux.

Source: nixCraft

Continue reading: Managing bootup services on Linux servers

Question: Is there a way to hide the version of Apache running on my server?

Answer: Yes, there certainly is, and there is a good reason to do so. While the version of Apache running on your server might be inconsequential to the average, it could be ammunition in the sneaky minds of would-be hackers. If they know which version of Apache you are running, they also know what vulnerabilities you have.

Ideally, you will always have the latest, most secure version, but security holes pop up and spread very quickly in the Internet underground, sometimes even before developers and security watchdogs can find them.

To hide your Apache version from all visitors, simply add two directive to your, Apache configuration file. On Redhat-based systems, you need to edit httpd.conf, which is found in the /etc/httpd directory. Find these two lines or add them:

ServerTokens ProductOnly
ServerSignature Off

That is all it takes. Now outside users will not be able to see what version of Apache server you are running no matter what software they have.

Continue reading: Hide Apache version from outside requests

Redhat Enterprise Linux, Fedora, and Centos have a convenient directory called “sysconfig”. It is located under the main /etc directory and contains many of the frequently-used configuration files necessary to operate a server. Often the configuration files are for command line options or very specific settings rather than the complete settings for a particular application.

For example, the httpd file under sysconfig is the configuration for the httpd server rather than Apache as a whole. In it you can set startup options and command flags. Other configuration files include crond (for configuring the crontab frequency), syslog (which configures the system log rotation), and spamassassin (setup for the spam filtering service).

One of the most important folders in sysconfig is “networking“. This is where a user sets up network devices, and devices that are automatically setup appear here as well. You would only need to configure this file if you were running a locally housed server. If your server is remote, this will never need to be changed and attempting to change it could cause you to lose the ability to access the server at all. I recommend browsing through the complete list of files in /etc/sysconfig and at least becoming aware of them, in case you need one of them in the future.

Continue reading: The sysconfig directory in Redhat-based Linux

Question: One of my applications in CentOS Linux is not working right. How do I reinstall it?

Answer: Early version of YUM did not have a “reinstall” function, but the newest version do. To reinstall a package, simply type as root:

yum reinstall package-name

If you are running a server with an older version of Fedora or other Redhat-based Linux distribution, your version of YUM may not support reinstallation. In such a case, you will have to manually reinstall it. From root, enter a command such as this to remove the files from the database:

rpm -e --justdb --nodeps packagename

YUM will then believe the package is not installed, even though it still is. Install as you normally would with:

yum install package-name

Continue reading: How to reinstall packages with YUM

The default update manager for Redhat-based Linux distributions is YUM, which is wonderful and all, but some people, especially those used to Debian-based distributions (such as Ubuntu), prefer to use APT for their updates. This is only for advanced users and should not be attempted on a server that already has working websites. Should something go wrong, you could break your distribution.

To install APT, follow these simple steps:

Download the corresponding Redhat Enterprise Linux package from this repository. Install it with:

rpm -Uhv package-name-release.rpm

Now to install APT, use YUM:

yum install apt

Now, you should be able to use APT to install and update Redhat, Fedora or CentOS packages. Tomorrow, you will learn how to use APT and some common tricks.

Continue reading: Using APT for installation and updates

Question: When I run updates with YUM (an update tool for Redhat, CentOS, or Fedora Linux), it seems like it takes forever. How can I make it faster?

Answer: Although there many things to consider when trouble-shooting speed issues, one specific YUM concern might be the speed of the mirror sites used for downloading packages. If download time seems to be the main concern (as opposed to actual installation time), installing yum-fastmirror should help.

This simple program will automatically seek out the fastest YUM mirror servers and then store the metadata in /var/cache/yum/timedhosts.txt. The plugin works by timing all the servers that come up in the mirror list and then selecting the one that is fastest for your location. Locations closer to you on less congested servers usually connect and send data faster. With yum-fastmirror, this can all be configured automatically.

To install the plugin, enter as root:

yum install yum-fastmirror

Continue reading: Making YUM Faster

Question: My dedicated server is showing a different timezone than my home computer. How can I set it to be on my timezone.

Answer: Generally speaking it does not matter if your remote server is on a different timezone. It will still function, but when scheduling maintenance, upgrades, and backups, it is crucial to make sure the time you schedule and announce is the actual time of the server. With the Linux “date” command, you can display and set the time of your server.

To display the current day, date, time, timezone, and year, simply type “date” from the command line. To set a new time, type “date -s” or “date –set” followed by the date, time, or both. For example, to set the time to 11:15:00, enter:

date +%T -s "11:15:00"

Changing the actual timezone is a little more involved. Read more about that here. In Redhat Enterprise Linux, Fedora, or CentOS, however, simply type:

redhat-config-date

Photo Source: Flickr

Continue reading: Setting the Correct Date for Your Linux Server