11 Mar

CentOS Overview and Knowledge Center

CentOS (Community Enterprise Operating System) is a Linux distribution that provides a free, enterprise-class, community-supported computing platform functionally compatible with its upstream source, Red Hat Enterprise Linux (RHEL).[5][6] In January 2014, CentOS announced the official joining with Red Hat while staying independent from RHEL,[7] under a new CentOS governing board.

In June 2006, David Parsley, the primary developer of Tao Linux (another RHEL clone), announced the retirement of Tao Linux and its rolling into CentOS development. Tao’s users migrated to the CentOS release via yum update.

In July 2009, it was reported in an open letter on the CentOS project web site that CentOS’s founder, Lance Davis, had disappeared in 2008. Davis had ceased contribution to the project, but continued to hold the registration for the CentOS domain and PayPal account. In August 2009, the CentOS team reportedly made contact with Davis and obtained the centos.info and centos.org domains.

CentOS Overview

In July 2010, CentOS overtook Debian to become the most popular Linux distribution for web servers, with almost 30% of all Linux web servers using it. Debian retook the lead in January 2012.

In January 2014, Red Hat announced that it would sponsor the CentOS project, “helping to establish a platform well-suited to the needs of open source developers that integrate technologies in and around the operating system”. As a result of these changes, ownership of CentOS trademarks was transferred to Red Hat, which now employs most of the CentOS head developers; however, they work as part of Red Hat’s Open Source and Standards team, which operates separately from the Red Hat Enterprise Linux team.

CentOS 7 arrived almost exactly one month after RHEL 7. Previous major version updates have taken significantly longer, with the bump from version 5 to 6 taking eight months. Point releases are usually quicker, but this is the first time we’e seen CentOS track its parent distro’s release schedule so closely.

CentOS6 CentOS7
Latest Release 6.1 7
Supports i386 Systems (32-bit Pentium, AMD) Yes Yes
Supports x86_64 systems (AMD64/EM64T) Yes Yes
Supports ia64 systems (Itanium2) No No
Supports s390/s390x systems (IBM zSeries & IBM S/390) No No
Supports PowerPC8le systems (IBM Power, Mac) No Yes
Supports IA-32 No Yes
Supports ARMv7hl systems No Yes
Supports AArch64 (arm64) systems No Yes
                            CPU / Memory / Filesystem limits (Tested/possible)
CentOS6 CentOS7
Maximum logical CPUs
x86 32 n/a
x86_64 448/4096 576/5120
Maximum memory
x86 16GB n/a
x86_64 12TB/64TB 12TB/64TB
Maximum filesize (ext3) 2TB 2TB
Maximum file system size (ext3) 16TB 16TB
Maximum filesize (ext4) 16TB 16TB
Maximum file system size (ext4) 16TB/1EB 50TB/1EB
Maximum filesize (XFS) 100TB 500TB
Maximum file system size (XFS) n/a 500TB
Maximum file system size (GFS2) 100TB 100TB
Maximum boot LUN size (BIOS) 2TB 2TB
Maximum boot LUN size (EFI) Any 50TB
Maximum x86 per-process virtual address space Approx 3GB
Maximum x86_64 per-process virtual address space 128TB 128TB
                              Recommended minimum requirements
CentOS6 CentOS7
x86 392M CLI/512M
other architectures 1G 1GB/logical CPU
Minimum/Recommended disk space 1G/5GB 10GB/20GB
CentOS6 CentOS7
Maximum number of cores on host 160
Maximum memory on host 2TB
Maximum number of vCPUs in fully virtualized guest (x86/x86_64) 160/160
Maximum memory in fully virtualized guest (x86/x86_64) 2TB/2TB
Minimum memory in fully virtualized guest (x86/x86_64) 512MB/512MB
                                        OS features (Kernel, Server, Client, etc.)
CentOS6 CentOS7
Kernel foundation Linux 2.6.32 Linux 3.10.0
Compiler/toolchain GCC 4.4 GCC 4.8.5
Languages supported 22
SELinux Yes Yes
Ext3 Performance Enhancements Yes Yes
Bluetooth support Yes Yes
Native POSIX Threading Library (NPTL) Yes Yes
Hyperthreading scheduler Yes Yes
IPv6 support Ready Logo Phase 2 Ready Logo Phase 2
Autofs V4 Yes Yes
Logical Volume Manager (LVM) Yes – LVM2 Yes – LVM2
Auditing Yes – audit Yes – audit
Compatibility libraries (toolchain) Yes – CentOS 4 & CentOS 5 Yes – CentOS 5 & CentOS 6
LSB support Yes – 4.0 Yes – 4.1
NFS Yes Yes
Web Server httpd 2.2.15 (apache) httpd 2.4.6 (apache)
Server Message Block (SMB) Samba-3.5.x (opt. 4.0.x) Samba-4.1.x
Database MySQL 5.1.x, PostgreSQL 8.4.x MariaDB 5.5.x, PostgreSQl 9.2.x
Programming Languages php 5.3.3, python 2.6.6, perl 5.10.1 php 5.4, python 2.7, perl 5.16.3
Desktop GUI X.org 7.4 Gnome 3.22, KDE 4.14
Graphics Evolution 2.32 , Thunderbird 60 X.org 7.7
eMail Client Firefox 60 Evolution 3.22, Thunderbird 60
Default browser Libreoffice Firefox 60
Office Suite Yes (mp3 with add. repos) Libreoffice
Multimedia capabilities Yes Yes (mp3 with add. repos)
Plug and Play Yes Yes


End-of-support schedule
According to the Red Hat Enterprise Linux (RHEL) life cycle, CentOS 5, 6 and 7 will be “maintained for up to 10 years” as it is based on RHEL. Previously, CentOS 4 had been supported for seven years.

CentOS version Release date Full updates Maintenance updates
3 19 March 2004 20 July 2006 31 October 2010
4 9 March 2005 31 March 2009 29 February 2012
5 12 April 2007 31 January 2014 31 March 2017
6 10 July 2011 10 May 2017 30 November 2020
7 7 July 2014 Q4 2020 30 June 2024

About Software Licence

software license is an agreement between you and the owner of a software program that allows you to do certain things that would otherwise be an infringement of copyright law. The software license usually answers questions such as

  • Where and how and how often can you install the program?
  • Can you copy, modify, or redistribute it?
  • Can you look at the underlying source code?

Software licence types

Proprietary is also known as “closed-source software” and non-free software. Proprietary software remains the property of its owner/creator and is used by end-users/organisations under predefined conditions and mainly used for commercial release.

Ex: Microsoft office, Microsoft Windows

Freeware is software, most often proprietary, usually small downloadable utilities. You don’t have the right to view the source code, and you do not have right to copy and redistribute the software. It mainly comes bundled with any operating system or you can download it from internet.

Ex: Adobe Reader, Free Studio, Skype, Internet Explorer etc.

Shareware (also known as trial ware or demoware) — Trial software that you can use free of charge for a limited time (usually 30 or 60 days). After that, when the trial period ends, the software must be purchased or uninstall.

Open source is software it’s source code is freely available to use, modify and redistribute. This software comes under GPL(General Public Licence)

Ex: GNU/Linux, Mozilla Firefox, VLC, VNC, Libre office etc.

What does GNOME mean?

GNOME (pronounced gah-NOHM) is a free and open source desktop environment and graphical user interface that runs on top of UNIX-based operating system.

What does GNU mean?

GNU (pronounced guh-noo) is a Unix-like computer operating system developed by the GNU project, Free Software Foundation. GNU operating system composed entirely of free software, ultimately aiming to be a complete Unix-compatible software system composed wholly of free software. GNU is a recursive acronym for “GNU’s Not Unix”, chosen because GNU’s design is Unix-like, but differs from Unix by being free software and containing no Unix code.

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