Jul 172011

centosOn 10 July CentOS 6 has been, finally, released.
CentOS-6.0 is based on the upstream release of Red Hat EL 6.0 and includes packages from all variants. All upstream repositories have been combined into one, to make it easier for end users to work with.

CentOS stands for Community ENTerprise Operating System and it exists to provide a free enterprise class computing platform and strives to maintain 100% binary compatibility with its upstream distribution, in this case Red Hat EL 6.


There are no CD images being released with CentOS-6, however there are some CD variants in the pipeline.
It’s possible to download a Live DVD image (4.1 GB) to install it or a cd to do a netinstall (around 173 MB).

The installation it’s made with anaconda, the Red Hat official installer, and it’s trivial for any system administrator, as file system the suggested for CentOS 6 it’s ext 4.

Package List

The package list is the same as red Hat 6, and being a Linux distribution for the Enterprise don’t expect the usual list of software you are used to see on Distributions for the Desktop (Ubuntu, Mint, Fedora).

So the important packages are:

kernel: 2.6.32 with some patches backported, some features are:

Control Groups:
Control groups are a new feature of the Linux kernel in Red Hat Enterprise Linux 6. Each control group is a set of tasks on a system that have been grouped together to better manage their interaction with system hardware. Control groups can be tracked to monitor the system resources that they use. Additionally, system administrators can use control group infrastructure to allow or to deny specific control groups access to system resources such as memory, CPUs (or groups of CPUs), networking, I/O, or the scheduler

Tickless: Previously the kernel implemented a timer that periodically queried the system to check if there were any outstanding tasks to process. Consequently, the CPU would remain in an active state, consuming unnecessary power. The kernel in Red Hat Enterprise Linux 6 enables the new tickless kernel feature, replacing the periodic timer interrupts with on-demand interrupts. The tickless kernel allows a CPU to enter longer sleep states when idle, and wake only when a task is queued for processing.

Aggressive Link Power Management (ALPM)
The kernel in Red Hat Enterprise Linux 6 features support for Aggressive Link Power Management (ALPM). ALPM is a power-saving technique that helps the disk save power by setting a SATA link to the disk to a low-power setting during idle time (i.e. when there is no I/O).

More info on the official Red Hat 6.0 kernel page

Other relevant packages are:

Apache http web server : httpd-2.2.15
java application server: tomcat6-6.0.24
PHP language: php-5.3.3

And if you really want to use a graphic interface Gnome 2.28 it’s available.

Why to use CentOS 6

CentOS it’s among the distributions more used as Web server, it’s completely released as Open source software and require no license to be used.
Another reason, for what i know, that people use CentOS it’s that it’s a clone of Red Hat 6, so in some data center they use RH 6 EL for some production server, and use CenOS for development servers or production servers that don’t need certifications.
In this way the system admins can use their knowledge, tools and script in both environments.

Why do not use CentOS 6

CentOS it’s a clone of Red Hat 6 EL, and it’s more than 6 months late, in the while Red Hat has moved to 6.1, and at the moment is not sure that CentOS 6 will backport the security fixes from RHEL 6.1.
Also you are choosing a clone operating system, while there are many original distributions that can be used without any problem as server, like Debian, Ubuntu Server, Slackware or Gentoo.

Personally i prefer to use Debian on any server that don’t need any certification and Red hat in servers that need a certification (Oracle, IBM or other commercial products), the drawback of this choice is that you must know 2 different distributions that use 2 different packaging system (deb and rpm).

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