Relationship between CentOS and RETHAT

At the beginning, I learned about liunx and did not know much about the relationship between rethat and centos. I searched some articles on the Internet and shared them with you. I would like to express my sincere gratitude to zhang45xiang for its technical blog. The following content is from zhang45xiang's blog at http://bbs.51cto.com/thread-0000625-1.html. I would like to thank all the experts at the same time. Cent

At the beginning, I learned about liunx and did not know much about the relationship between rethat and centos. I searched some articles on the Internet and shared them with you.

I would like to express my sincere gratitude to zhang45xiang for its technical blog. Many of the following content is from zhang45xiang's blog. The address is http://bbs.51cto.com/thread-824625-1.html and I would like to thank Baidu Baike.

 

CentOS is short for Community ENTerprise Operating System. Many of us call it a Community ENTerprise Operating System. No matter how you call it, it is a release version of linux.

CentOS is a secondary release of Red Hat Linux Enterprise Edition. Since Red Hat Linux Enterprise Edition only provides technical support to paying users, this is unforgivable to Everbright open source writers, right? Pan is here to compete? Qin? Critical? Cool? Xie Xiaoji Yu> what about the trigger of a trigger upon a ship ??? Comfort? Why? The released version of entOS is almost identical to the rethat version, but it is free of charge. However, in addition to the problem, solving the problem will naturally be slower than spending money.

Most of the software packages that constitute RHEL are released based on the GPL protocol, which we often call open source software. Because of this, Red Hat also follows this protocol, publish the software package that constitutes RHEL. Anyone who follows the GPL protocol can develop and release the software on the basis of the original software. In this way, CentOS is a Linux release version that constitutes a clone and reproduction of RHEL on the basis of RHEL release. The clone version of RHEL is not only CentOS, but also White Box Enterprise Linux and TAO Linux and Scientific Linux.

Although it is a RHEL clone, it is not exactly the same. The clone is 100% interchangeable (Really ?). However, it is not guaranteed that the software corresponding to RHEL can work normally for 100% of CentOS. In addition, the security vulnerability fixes and software package upgrades correspond to the paid services and technical support of RHEL. The delay may also occur for several stars and months in a few days.

 

Features of CentOS

In the full name of CentOS, we can see that Enterprise OS, that is to say, the Enterprise system is not an Enterprise-level system, but it can provide the elements required by Enterprise-level applications.
For example:
Stable Environment
Long-term update support
Highly conservative
Large-scale Systems can also achieve good performance.

CentOS meets the requirements of the above elements. The releases of the above elements are also similar to those of Fedora, Fedora and CentOS. But for CentOS, Fedora provides more new functions and software, fast updates and other features, which adds a lot of work in terms of stability and management. The system environment required by enterprises should be an efficient and stable system environment that can be used for a long time after being built. Therefore, the fast-Updating system environment like Fedora does not correspond to the application of enterprises. On the other hand, CentOS can meet the above requirements. Among the many RHEL clone versions, CentOS is outstanding.

 

However, this world is a capital world, and the viability of free organizations with no money is limited. What's more, the red hat company is optimistic about CentOS-based earning and drinking activities, in 2014, centos and RedHat became a family.

After CentOS is added to the red hat, it remains unchanged:

1. CentOS continues to be free of charge

2. Keep the content-driven network center unchanged

3. Fixed Bug, Issue, and emergency handling policies

4. Red Hat Enterprise Linux and CentOS firewalls still exist.

The changes are:

1. We work for Redhat, not RHEL.

2. Red Hat sponsors the construction system and initial content delivery resources

3. Some development resources, including source code, will be easier to obtain.

4. Avoiding the original and Red Hat Legal Issues

 

CentOS is a release of Linux.

Features:

1. CentOS can be understood AS the Red Hat AS series! It is released after improvements to Red Hat! There is no difference between various operations and uses and red hat!

2. CentOS is free of charge. There is no problem that red hat AS4 requires serial numbers.

3. The yum command exclusive to CentOS supports online upgrades and immediate updates to the system. Unlike red hat, you don't have to pay for the support service!

4. CentOS fixed many red hat as bugs!

5. CentOS version Description: CentOS3.1 is equivalent to red hat AS3 Update1 CentOS3.4. It is equivalent to red hat AS3 Update4 CentOS4.0 and is equivalent to red hat AS4 (now centos 5)

6. CentOS homepage http://www.centos.org


Relationship between CentOS and RHEL:

There are two methods for RHEL release. One is the binary distribution method, and the other is the source code distribution method.

No matter which release method you use, you can obtain it for free (for example, download it from the Internet) and release it again. However, if you use their online upgrades (including patches) or consulting services, you must pay for them.

RHEL has always provided source code distribution methods. CentOS is to re-compile the source code released by RHEL to form a usable binary version. Since the LINUX source code is GNU, it is valid from obtaining the RHEL source code to compiling a new binary. Only REDHAT is a trademark, so the trademark of REDHAT must be removed from the new release.

REDHAT's attitude towards this release is: "We don't really oppose this release. Users who actually pay for it do not pay attention to the system itself, but the commercial services we provide. "

Therefore, CentOS can obtain all RHEL functions and even better software. However, CentOS does not provide commercial support to users, and of course it is not subject to any commercial responsibilities.

If you want to transfer your RHEL to CentOS, you do not want to pay for the RHEL upgrade. Of course, you must have rich UNIX experience, so RHEL's commercial technical support is not important to you.

However, if you are a business-type enterprise, we recommend that you purchase RHEL software and services. In this way, you can save on IT management costs and get professional services.

In a word, choosing CentOS or RHEL depends on whether your company has the corresponding technical strength.

Bytes -------------------------------------------------------------------------------------------------------
A post on the Linux version is provided for your reference.

What are common Linux versions? What is CentOS?
Linux is short for GNU/Linux. It is usually the general name of various Linux releases.
Common Linux Manufacturers include Redhat/Novell.

Redhat has two major Linux product series, one of which is the free Fedora Core series.
It is mainly used for desktop versions and provides support for many new features.
Another product series is the paid Enterprise series, which is divided into AS, ES, WS, and other branches.

Advanced Server, abbreviated. Based on the standard Linux kernel,
It improves performance and reliability, and integrates drivers of many common servers.
Allows you to easily identify disk arrays and other devices for common rack-mounted servers such as IBM, DELL, and HP.

AS major version 2.x/ 3.x/ 4.x, which is what we call AS3/AS4
Each version has several upgrades. For example, after the first release of AS4, some updates are encountered.
AS4 Update1 will be released, and AS4 Update2/Update3 will appear in the future
For short, AS4u1, AS4u2, and AS4u3. This is very similar to Microsoft's release form,
Microsoft's Windows NT4 goes from SP1 to SP6, and Windows2000 goes from SP1 to SP4 ....

AS, the major package versions included in these Update versions are different.
Otherwise, problems may occur easily. The installation packages of Prima and Plesk have specific designs for various releases.
The download page usually identifies the versions and update systems supported.

Elasticsearch is a simplified version of. The difference between it and the common AS series is that AS supports more than 4 CPUs,
Elasticsearch supports only two CPUs. AS and ES are no different in most packages,
Only a few software packages such as the kernel are different.
The prices of AS and elasticsearch vary greatly. elasticsearch is usually used in OEM versions purchased with servers.
For example, if you purchase a DELL server, the Linux server will be the elasticsearch series.
If you want to match the AS series, you need to spend thousands more.

WS is a further simplified version of ES. It is mainly used in the desktop office market in China.

Both the Redhat Fedora Core Linux and Enterprise Linux must comply with the GNU protocol.
You need to publish your own source code.
Therefore, for free Fedora Core Linux, you can directly download the ISO dial from the Redhat website,
You can also download the srpm iso, that is, the package source code CD.
The paid Enterprise Linux series is a commercial product, so the ISO file cannot be downloaded from the website,
You must purchase an authorized account.
Since Enterprise Linux also needs to follow the GNU protocol, the source code must be published.
Therefore, on the Redhat website, you can obtain the SRPM Source Code ISO file of the AS/ES/WS series.
These files can be freely downloaded, modified, and re-compiled.

A project named Community Enterprise Operating System was born.
The abbreviation is CentOS. The CentOS community downloads all the source code on the Redhat website,
Re-compile. After re-compilation, because AS/ES/WS is a commercial product,
You must change the Logo and Logo of all Redhat to your own CentOS Logo.
For example, after compiling the original SRPM source code of AS4, it becomes CentOS 4.0.
After the source code of AS4Update1 is compiled, it becomes CentOS4.1.
After the source code of AS4Update2 is compiled, it becomes CentOS4.2.
Similarly, CentOS 3.x/ 4.x corresponds to the corresponding version.

Therefore, CentOS is the free version of Redhat AS/ES/WS.
With CentOS, you can get the same performance and experience AS/ES.
In addition to standard numbers 1 ~ 4 or 1 ~ 5, except for several ISO sheets,
It also provides a Server disc that minimizes 1CD. The system installed on the Server Disc,
Is a minimal Linux kernel with commonly used httpd/mysql packages.
Does not include useless software such as Xwindows desktop for servers.