The difference and connection between CentOS and Redhat

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The relationship between CentOS and Redhat:
There are two ways in which Redhat is released: The binary distribution and the way the source code is issued. Either way, you can get it for free (for example, download it from the Internet) and publish it again. But if you use their online upgrades (including patches) or consulting services, you'll have to pay.
Redhat has always provided the source code for distribution, and CentOS is the Redhat release source to recompile once, to form a binary version that can be used. Since the source code for Linux is GNU, it is legal to get the source code from Redhat to the new binary. Just Redhat is a trademark, so you have to remove Redhat's trademark in the new release.
Redhat's attitude to this distribution is: "We are not really against this distribution, the users who really pay us, they value not the system itself, but the business services we provide." "So, CentOS can get all the features of Redhat, even better software. However, CentOS does not provide commercial support to users and, of course, is not responsible for any business.
If you want to transfer your redhat to CentOS, you do not want to pay for the Redhat upgrade. Of course, you have to have a lot of experience with UNIX, so Redhat's business technical support is not important to you. But if you are a purely business-oriented enterprise, then it is recommended that you buy Redhat software and purchase the appropriate services. This will save you money on IT management and get professional services.
In a word, the choice of CentOS or redhat depends on whether your company has the appropriate technical force.
1. CentOS can be fully understood as redhat as series! It was completely improved after the Redhat as was released! All kinds of operation, use and Redhat no difference!
2, CentOS is completely free, there is no problem like Redhat as series need serial number.
3, CentOS exclusive yum command Support Online upgrade, can update the system immediately, not like Redhat need to pay to buy support services!
4. CentOS fixes many redhat as bug!
5. CentOS Version Description:
CentOS4.0 equivalent to Redhat AS4
CentOS4.1 equivalent to Redhat AS4 U1
CentOS4.2 equivalent to Redhat AS4 U2
CentOS4.3 equivalent to Redhat AS4 U3
CentOS4.4 equivalent to Redhat AS4 U4

Here's a look at Red Hat.
Redhat has two major Linux product lines:
One is the free Fedora Core series, primarily for desktop editions, providing support for a number of new features.
Note
Red Hat's products include Redhat Linux (such as redhat8,9) and enterprise-issued versions of Red Hat Enterprise Linux, which can be obtained and used free of charge via web FTP, but in 2003, Red Hat Linux discontinued development, which is why there is no Redhat10, and its projects are superseded by Fedora Project, which is released under the name Fedora Core and is available free of charge to ordinary users. The Linux distribution of Fedora Core is updated very quickly and has a new version about half a year or so, the current version is Fedora Core 6, the Fedora Core test has a strong flavor, each release has new features added to it, Successful results will be implemented in the release of the Dow Rhel. In spite of this, the frequent improvement of the unstable products for the enterprise is not the best choice, most enterprises will choose the paid Rhel products. ）

Second, the enterprise series of charges, this series is divided into: As/es/ws and other branches. The corporate version of Red Hat Enterprise Linux:redhat, Jane writing: RHEL. Includes the following versions:
1. Red Hat Enterprise Linux as
Red Hat Enterprise Linux as (Advanced Server) is the top-of-the-range product in Enterprise Linux solutions and is designed for the enterprise's off-the-box applications and data centers. Red Hat Enterprise Linux as is the only product that supports the IBM I series, P-series, and Z-series/s-390 systems. On the Intel X86 platform, Red Hat Enterprise Linux as can support more than 2 CPUs and more than 8GB of memory. The typical Red Hat Enterprise Linux as application environment is as follows:
Database and database application software
Web and middleware
CRM, ERP,SCM
2. Red Hat Enterprise Linux es Red Hat corporate linux es (Entry Server)
Provides a server operating system for the Intel X86 market, from Enterprise Portal to enterprise mid-tier applications. It supports 1-2CPU and systems with less than 8GB of memory. It provides the same performance as Red Hat Enterprise Linux as, except that it supports smaller systems and lower costs. The typical Red Hat Enterprise Linux ES application environment is as follows:
Corporate Web Architecture
Network Edge Applications (DHCP, DNS, firewalls, etc.)
Mail and file/print services
Small and medium scale database and departmental application software
3. Red Hat Enterprise Linux WS
Red Hat Enterprise Linux WS (Workstation) is a desktop/client partner for Red Hat Enterprise Linux as and ES. Red Hat Enterprise Linux ws supports 1-2CPU's Intel and AMD systems, which are the best environments for desktop applications. It contains a variety of commonly used desktop applications (Office Tools, mail, instant messaging, browser, etc.) and can run a variety of customer-server configuration tools, software development tools, and a variety of application software (such as EDA and Oil/gas application software). Red Hat Enterprise Linux ws and server products are compiled from the same source code, but it does not provide network service functionality (such as DNS and DHCP) and is only suitable for client applications.
(Note: Advanced Server, abbreviation is as.) As on the basis of the standard Linux kernel, the performance is enhanced and the reliability is improved, and the drivers of many common servers are integrated. Devices such as disk-array cards for common rack servers such as IBM/DELL/HP can be easily identified. As major version 2.x/3.x/4.x, which is what we call As3/as4, there are several upgrades for each version, such as the first AS4 introduced, and some updates have been encountered. At this point will be released AS4 Update1, in the future there will be AS4 update2/update3, such as the emergence of abbreviation AS4U1/AS4U2/AS4U3. This and Microsoft's release form is also very similar, Microsoft's Windows NT4 from SP1 to sp6,windows2000 from SP1 to SP4 and so on. As these update versions contain a certain difference between the major package versions, it is best not to mix them up, otherwise it is easy to have problems. Prima and Plesk's installation packages, for various distributions have a targeted design on the download page, which is usually identified, which versions and which update systems are supported.
ES, is a lite version of AS. The difference between him and the common as series is that as supports up to 4 CPUs, and ES supports only two CPUs. As and Es are no different on most packages, only a few packages on the kernel. The price difference between as and ES is larger, usually es used in the OEM version purchased with the server. For example, if you purchase a Dell server, the Linux pairing will be the ES series. If you want to match the as series, you need to spend thousands of yuan more.
WS, is a further simplified version of ES, mainly for the Enterprise internal desktop office market, less domestic use. ）
Redhat's Fedora Core Linux and Enterprise Linux are subject to the GNU protocol, which requires the release of its own source code. So, for free Fedora Core Linux, you can download the ISO engraving directly from the Redhat website and download it to the srpm ISO, the package source CD. For paid Enterprise Linux series, is a commercial product, so the website can not be downloaded to the ISO file, need to purchase the official authorized party. Because Enterprise Linux also needs to follow the GNU protocol, the source code must be published. So on the Redhat website, you can get the AS/ES/WS series of srpm source ISO files. These files can be downloaded freely, modify the code, and recompile the use.

Community Enterprise Operating System Project was born, its abbreviation is both CentOS. The CentOS community will download all the source code on Redhat's website and recompile it. After recompilation, since AS/ES/WS is a commercial product, all Redhat logos and logos must be changed to their own CentOS logo. For example, the AS4 original srpm source code compiled, it became the CentOS 4.0. After compiling the source code of AS4UPDATE1, it becomes the CentOS4.1. After compiling the source code of As4update2, it becomes the CentOS4.2. Similarly, the 3.x/4.x of CentOS corresponds to the corresponding version.
So we say that CentOS is the free version of Redhat's as/es/ws. With CentOS, you get the same performance and feel as as/es. In addition to providing a standard number 1~4 or several ISO's, CentOS also provides a minimal 1CD server CD. The system installed with the server CD-ROM is a minimized Linux kernel plus common httpd/mysql and other packages, not including Xwindows desktop and other useless software for the server.

So you can find the corresponding Red Hat package for the RPM package of CentOS.

http://www.linuxdiyf.com/viewarticle.php?id=218621

Differences and linkages between CentOS and Redhat