Questions about CentOS 4

1. Are there any alternative upgrade methods to get to CentOS 4.x?

While a lot of people have posted routes and methods to move to CentOS 3.4 to CentOS 4 - the only reliable method that seems to work under different conditions is to boot the CentOS 3.4 machine using CD-1 from CentOS4, and type 'linux upgradeany' at the boot prompt. CentOS 4 will then upgrade the CentOS 3.4 machine, and make all changes required to the filesystem in order to get a functional CentOS 4 install. Once run through, its always a good idea to check the functions you use often, server settings and UI components.

Additional comments by JohnnyHughes:

2. Where do I get the package signing key for CentOS 4?

You need to install the CentOS RPM signing key. It is not installed as part of the base system install for security reasons. This provides you the opportunity to validate the key before installing it on your system. RPM has the capacity to retrieve the key from a Centos Mirror:

rpm --import

(as root) will install ('import') the CentOS 4 package signing key for RPM to use to confirm a validly signed package. Please note that it is safer to import the copy of the key from the install ISO media. It is in the root directory of each ISO, as RPM-GPG-KEY, and the same key is present on disc 1 as RPM-GPG-KEY-CentOS-4. The reason this is safer is that a CD is immutable media, and when you verify ISO MD5SUMs, you are implicitly also verifying the key. As a backstop, this key is as follows:

Version: GnuPG v1.2.1 (GNU/Linux)

If there is any question as to the validity of the key, please enquire; if a forged key is encountered, please send details, and return contact details to reach you to:

3. What is CentOS 4?

CentOS-4 is a freely distributable OS built from the source at: Before building the OS, non-free packages are altered. Non-free packages would include those encumbered with a non-redistributable copyright or trademark. CentOS-4 supports x86 (i586 and i686), x86_64 (AMD64 and Intel EMT64), ia64, ppc, s390, s390x, sparc and alpha architectures (ppc and sparc are currently BETA). Updates are distributed via YUM repositories.

4. What is the centosplus repository for CentOS-4?

The centosplus repo contains packages contributed by CentOS Developers and the Users. These packages might replace rpm's included in the core Distribution. You should understand the implications of enabling and using packages from this repository. See this Readme.txt file for the latest information for CentOS-4 centosplus repo.

There also is a Wiki page about all the different Repositories for CentOS.

5. What is KBS CentOS Extras?

KBS CentOS Extras is a repository that is based on Fedora Extras and built to work with CentOS-4 i386 and x86_64 arches. It is not an official CentOS repository, but it is currently maintained by Karanbir Singh (one of the CentOS-4 developers) so it is a very good source of programs that are not included with CentOS-4. You can find out how to get the programs for CentOS Extras here:

For other Repositories also compatible with CentOS4 see this Page.

6. Who are the CentOS 4 developers and how can I contact them?

Name (IRC nick)

You can easily contact the CentOS-4 developers via the CentOS General Discussion Mailing List or on the #centos channel on IRC You can get help from other users at the CentOS-4 Forums

7. Is RHGFS and RHCS available for CentOS-4?

Yes, we have released Global File System 6.1 and Cluster Suite 4.0 for CentOS-4. They are available from this repository.

8. Is Red Hat® Directory Server available for CentOS-4?

No. Red Hat® Directory Server 7.1 and Red Hat Console and Administration Server have not been released. When the SRPMS are released, we will build it for CentOS-4.

You can install Fedora Directory server RPMs provided at Choose the "Fedora Core 3 and RHEL4" version for CentOS 4.x

9. How long will CentOS-4 updates be supported?

We intend to support CentOS-4 updates until Feb 29, 2012. The current plan is this:

10. How do I use LVM2 with CentOS-4?

The basic answer is that you create Physical Volumes (PVs) using pvcreate and then either create or extend Volume Groups (VGs) with the PVs, the commands for this are vgextend, vgcreate, vgremove among others. Next you would create or extend Logical Volumes (LVs) in the VGs. The commands for that are lvcreate, lvextend, lvremove. Once you have taken care of the LVs, you would extend the file system (ext2 or ext3) using the ext2online command. Here are some detailed references with examples for using LVM2 on ext3:

11. How do I install software RAID CentOS4?

There are two kinds of RAID: hardware RAID and software RAID. The first thing that everyone needs to understand is that many of the new SATA RAID motherboards do not have real hardware RAID, but instead contain a software RAID. The hardware manufacturer provides a software driver to have Windows recognize this a RAID, however it is not hardware RAID, any more than winModems are full hardware modems. So, in these instances, software RAID on Linux can be used. Here is documentation on how to do software RAID on CentOS:

Man pages: mdadm, mdadm.conf, md

After installation of a software RAID1, you must install GRUB on both partitions. Here is a way to do that:

Hardware RAID is specific to each controller. There are hardware drivers and software to manage the arrays before installation. To CentOS, a hardware RAID configuration looks like one device to install on. All the RAID functions are handled by the hardware controller.

12. What are the different types of files available in the CentOS 4 isos directory?

CentOS ISO Directory

There are several possible files within each ISO directory.

  1. ISO files {end in .iso} - These files are the images themselves. You would burn these files as an image, once downloaded, to use to install CentOS. See this documentation on how to burn ISO files to disc:

  2. Torrent files {end in .torrent} - Torrent files will allow you to download the CD using Bittorrent. This is the only way to get ISOs from the servers. If you are using CentOS, you can get the latest el3 (for CentOS-3) or the el4 (for CentOS-4) version of bittorrent from Dag Wieer's repository: Other OS users can get the latest bittorrent client from:

  3. MD5 files - Other files that are available are the MD5 sums of the iso files in the directory. You can check the md5 sum of the file on your PC to ensure it was transfered properly to your computer and that none of the bits were scrambled, dropped, etc. See this guide for checking the md5 sum of an ISO:

Single Server CD

The Single Server CD is an ISO that contains most of the items required for basic server setup (without a GUI) on a single CD. This was created for those who want to download 1 CD and be able to do a functional install. Obviously, we can't fit everything from the 4 CD set onto 1 CD, but we may not have the packages JUST right. We welcome feedback to the packages included in the Single Server CD, so if you need something not there, let us know. The best way to provide feedback to the CentOS developers is via the CentOS-Devel mailing list:

Once you use the Single Server CD to install, you can use yum or up2date to add programs that you might need, and it functions just like any other CentOS install. Especially good is the "yum groupinstall" feature. See this link for more help with using yum:

Full Arch CDs

There are a number of CDs that contain the full install for an architecture (ARCH). There are normally 3 or 4 CDs and they are numbered as either:


or like this:


These CDs are the RPMS that need to be installed and the first disc is bootable to do the install.


DVDs are normally available for each version, but the ISO files are not normally included in the ISO directory. You can download the CentOS DVD's via bittorrent. This is because of the following reasons:

  1. Files greater than 2 GB are not served properly by the default apache included in CentOS (and many other distros), so external (public) CentOS mirrors would end up with large files that they could not serve taking up space on their servers.
  2. Including all DVDs in the mirror would increase the size of the CentOS mirror by 50% (it would be 1.5 x current). As we continue to release new arches and support for new versions, this would cause the size of CentOS to become to large; reducing the number of people who could mirror it for us externally.

FAQ/CentOS4 (last edited 2014-04-25 13:54:57 by AnssiJohansson)