PowerEdge: How to migrate from Red Hat Enterprise Linux to CentOS

Summary: This article provides the procedure to migrate from Red Hat Enterprise Linux to CentOS.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
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Instructions

The minimum supported version of Red Hat Enterprise Linux is 7.4.

If the Red Hat Enterprise Linux version is earlier than 7.4, then the system must be upgraded before completing this process.



Procedure:

Note: For example purposes, this article provides the migration procedure from Red Hat Enterprise Linux v7.5 to CentOS v7.
  1. Log in to the SSH.
  2. Run the following command to check the current release:
    Sample output: 
    cat /etc/*release
[root@RHEL75_SDS1 /]# cat /etc/*release
NAME="Red Hat Enterprise Linux Server"
VERSION="7.5 (Maipo)"
ID="rhel"
ID_LIKE="fedora"
VARIANT="Server"
VARIANT_ID="server"
VERSION_ID="7.5"
PRETTY_NAME="Red Hat Enterprise Linux Server 7.5 (Maipo)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:redhat:enterprise_linux:7.5:GA:server"
HOME_URL="https://www.redhat.com/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
 
REDHAT_BUGZILLA_PRODUCT="Red Hat Enterprise Linux 7"
REDHAT_BUGZILLA_PRODUCT_VERSION=7.5
REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="7.5"
Red Hat Enterprise Linux Server release 7.5 (Maipo)
Red Hat Enterprise Linux Server release 7.5 (Maipo)
  3. Run the following command to check which Red Hat Enterprise Linux packages are installed:
    Sample output: 
    rpm -qa |egrep  "rhn|redhat"
[root@RHEL75_SDS1 /]# rpm -qa |egrep  "rhn|redhat"
rhn-check-2.0.2-21.el7.noarch
rhnlib-2.5.65-7.el7.noarch
redhat-support-tool-0.9.10-1.el7.noarch
redhat-indexhtml-7-11.el7_0.noarch
redhat-release-server-7.5-8.el7.x86_64
rhn-setup-2.0.2-21.el7.noarch
redhat-logos-70.0.3-6.el7.noarch
rhn-client-tools-2.0.2-21.el7.noarch
yum-rhn-plugin-2.0.1-10.el7.noarch
redhat-support-lib-python-0.9.7-6.el7.noarch
rhnsd-5.0.13-10.el7.x86_64
  4. Run the following command to remove the packages with yum: 
    yum remove rhnlib redhat-support-tool redhat-support-lib-python
  5. Run the following command to check for the remaining Red Hat Enterprise Linux packages that are installed:
    Sample output: 
    rpm -qa |egrep  "rhn|redhat"
redhat-indexhtml-7-11.el7_0.noarch
redhat-release-server-7.5-8.el7.x86_64
redhat-logos-70.0.3-6.el7.noarch
  6. Run the following commands to remove the remaining packages: 
    rpm -e --nodeps redhat-release-server redhat-logos redhat-indexhtml yum
		rpm -e subscription-manager subscription-manager-rhsm subscription-manager-rhsm-certificates
  7. Run the following command again to check if no Red Hat Enterprise Linux packages are present: 
    rpm -qa |egrep  "rhn|redhat"
  8. Run the following commands to delete the Red Hat Enterprise Linux folders: 
    rm -rvf /usr/share/doc/redhat-release/
rm -rvf /usr/share/redhat-release/
  9. Run the following commands to remove the subscription manager: 
    rpm -e subscription-manager
rpm -e subscription-manager-rhsm
rpm -e subscription-manager-rhsm-certificates
  10. Run the following commands to remove the extra unused packages: 
    rpm -e katello-agent
rpm -e katello-ca-consumer-{XXX}
rpm -e katello-host-tools
rpm -e katello-host-tools
rpm -e katello-host-tools-fact-plugin
rpm -e pulp-rpm-handlers
rpm -e python-gudev-147.2-7.el7.x86_64
rpm -e libgudev1-219-67.el7.x86_64
rpm -e python-pulp-rpm-common-2.13.4.9-1.el7sat.noarch
rpm -e python-pulp-agent-lib-2.13.4.16-1.el7sat.noarch
rpm -e python-pulp-common-2.13.4.16-1.el7sat.noarch
  11. Remove the remaining extra unused packages:
    Select from options:
    • Run the following command: 
      yum remove systemd-python-219-67.el7.x86_64
    • Run the following commands: 
      rpm -e abrt-console-notification-2.1.11-55.el7.centos.x86_64
rpm -e abrt-cli-2.1.11-55.el7.centos.x86_64
rpm -e abrt-addon-python-2.1.11-55.el7.centos.x86_64
rpm -e systemd-python-219-67.el7.x86_64
  12. Run the following command to copy the ISO file to the system and place it in /tmp/ folder: 
    winscp iso to server or scp iso to server
  13. Run the following commands to mount CentOS to a location for use:
    Sample output: 
    cd /tmp
mount -o loop /tmp/CentOS-7-x86_64-DVD-1804.iso /mnt/cdrom/
mount: /dev/loop0 is write-protected, mounting read-only
df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root  18G  6.8G   11G  39% /
devtmpfs               2.0G     0  2.0G   0% /dev
tmpfs                  2.0G  306M  1.7G  16% /dev/shm
tmpfs                  2.0G   12M  2.0G   1% /run
tmpfs                  2.0G     0  2.0G   0% /sys/fs/cgroup
/dev/sda1              497M  142M  355M  29% /boot
tmpfs                  394M     0  394M   0% /run/user/0
/dev/loop0             4.2G  4.2G     0 100% /mnt/cdrom
  14. Run the following commands to install the GPG key and the CentOS system packages:
    Sample output: 
    rpm --import /mnt/cdrom/RPM-GPG-KEY-CentOS-7
cd /tmp/
mkdir packages
cp -v /mnt/cdrom/Packages/yum-plugin-fastestmirror-1.1.31-45.el7.noarch.rpm /tmp/packages/
cp -v /mnt/cdrom/Packages/yum-3.4.3-158.el7.centos.noarch.rpm /tmp/packages/
cp -v /mnt/cdrom/Packages/centos-logos-70.0.6-3.el7.centos.noarch.rpm /tmp/packages/
cp -v /mnt/cdrom/Packages/centos-release-7-5.1804.el7.centos.x86_64.rpm /tmp/packages/
cd /tmp/packages/
rpm -Uvh packages/*.rpm
Preparing...                       ################################# [100%]
Updating / installing...
1:yum-plugin-fastestmirror-1.1.31-4################################# [ 25%]
2:yum-3.4.3-158.el7.centos         ################################# [ 50%]
3:centos-release-7-5.1804.el7.cento################################# [ 75%]
4:centos-logos-70.0.6-3.el7.centos ################################# [100%]
  15. Run the following commands to move the repo to /root/ folder to make a local repo through the ISO: 
    cd /etc/yum.repos.d/
mkdir /root/orig_repos/
mv *.repo /root/orig_repos/
ls /etc/yum.repos.d/
    Note: It should return to an empty directory.
     
  16. Run the following commands to create an ISO repo: 
    cd /etc/yum.repos.d/
		vi centos77-iso.repo
		cat /mnt/cdrom/.discinfo
    Note: For the repo, the .discinfo is different for each CD image.

    Sample output: 
    vi /etc/yum.repos.d/centos77-iso.repo 
cat centos77-iso.repo
[repository]
imediaid=1567770002.381990
name=CentOS-Server-7
baseurl=file:///mnt/cdrom
gpgkey=file://etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
enabled=1
gpgcheck=1
  17. Run the following commands to prepare the yum:
    Sample output: 
    yum clean all
Loaded plugins: fastestmirror, langpacks
Cleaning repos: repository
Other repos take up 25 M of disk space (use --verbose for details)

    Sample output: 
    yum repolist
Loaded plugins: fastestmirror, langpacks
Determining fastest mirrors
repository                                                | 3.6 kB  00:00:00
(1/2): repository/group_gz                                | 165 kB  00:00:00
(2/2): repository/primary_db                              | 3.2 MB  00:00:00
repo id                            repo name                               status
repository                         CentOS-Server-7                         4,067
repolist: 4,067c
  18. Run the following command to upgrade or update the yum: 
    yum update
  19. Run the following command to update the grub boot menu: 
    grub2-mkconfig -o /boot/grub2/grub.cfg
  20. Place the SDS into maintenance mode through VxFlex UI or CLI.
  21. Run the following command to reboot: reboot
    Note: After reboot, it should come online as a CentOS system.
  22. Run the following command to check the release:
    Sample output: 
    cat /etc/*release
CentOS Linux release 7.7.1908 (Core)
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"
		 
CENTOS_MANTISBT_PROJECT="CentOS-7"
CENTOS_MANTISBT_PROJECT_VERSION="7"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="7"
		 
CentOS Linux release 7.7.1908 (Core)
CentOS Linux release 7.7.1908 (Core)
  23. Exit the SDS from the maintenance mode and go to the next server.
    Note: If you must apply the rolled up CentOS patches from the ZIP bundle that is at the Dell support page or flexnet, do this step after the patches are applied.

Affected Products

PowerEdge XR2, PowerEdge FC640, PowerEdge M640, PowerEdge M640 (for PE VRTX), PowerEdge MX5016s, PowerEdge MX7000, PowerEdge MX740C, PowerEdge MX750c, PowerEdge MX760c, PowerEdge MX840C, PowerEdge R240, PowerEdge R250, PowerEdge R260, PowerEdge R340 , PowerEdge R350, PowerEdge R360, PowerEdge R440, PowerEdge R450, PowerEdge R470, PowerEdge R540, PowerEdge R550, PowerEdge R640, PowerEdge R6415, PowerEdge R650, PowerEdge R650xs, PowerEdge R6515, PowerEdge R6525, PowerEdge R660, PowerEdge R660xs, PowerEdge R6615, PowerEdge R6625, PowerEdge R670, PowerEdge R740, PowerEdge R740XD, PowerEdge R740XD2, PowerEdge R7415, PowerEdge R7425, PowerEdge R750, PowerEdge R750XA, PowerEdge R750xs, PowerEdge R7515, PowerEdge R7525, PowerEdge R760, PowerEdge R760XA, PowerEdge R760xd2, PowerEdge R760xs, PowerEdge R7615, PowerEdge R7625, PowerEdge R770, PowerEdge R7715, PowerEdge R7725, PowerEdge R840, PowerEdge R860, PowerEdge R940, PowerEdge R940xa, PowerEdge R960, PowerEdge T130, PowerEdge T140, PowerEdge T150, PowerEdge T160, PowerEdge T30, PowerEdge T330, PowerEdge T340, PowerEdge T350, PowerEdge T360, PowerEdge T40, PowerEdge T430, PowerEdge T440, PowerEdge T550, PowerEdge T560, PowerEdge T630, PowerEdge T640, PowerEdge XR11, PowerEdge XR12, PowerEdge XR4000r, PowerEdge XR4000w, PowerEdge XR4000z, PowerEdge XR4510c, PowerEdge XR4520c, PowerEdge XR5610, PowerEdge XR7620, PowerEdge XR8000r, PowerEdge XR8610t, PowerEdge XR8620t, Red Hat Enterprise Linux Version 7, Red Hat Enterprise Linux Version 9, Red Hat Enterprise Linux Version 8 ...
Article Properties
Article Number: 000205470
Article Type: How To
Last Modified: 13 Mar 2025
Version:  2
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