Todos sabemos das mudanças ocorridas com o CentOS, visando alternativas de migração, optei por migrar para Oracle Linux, além das funcionalidades implementadas pelo Oracle e a compatibilidade que o OL tem em relação ao CentOS/RHE, tenho utilizado OL por muitos anos como padrão em servidores Linux, segue abaixo uma forma simples de migrar de CentOS para OL.
Lembre-se de aprovar o processo em ambientes de teste ou tirar um instantâneo da máquina virtual antes da migração.
1- Verifique no mínimo 5GB de espaço em disco em /var/cache:
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 45G 3.6G 42G 8% /
devtmpfs 895M 0 895M 0% /dev
tmpfs 911M 0 911M 0% /dev/shm
tmpfs 911M 10M 901M 2% /run
tmpfs 911M 0 911M 0% /sys/fs/cgroup
/dev/sda1 1014M 170M 845M 17% /boot
tmpfs 183M 0 183M 0% /run/user/0
[root@localhost ~]#2 – Check current kernel and version:
[root@localhost ~]# cat /etc/*-release | grep PRETTY
PRETTY_NAME="CentOS Linux 7 (Core)"
[root@localhost ~]# uname -r
3.10.0-1160.42.2.el7.x86_643 – List repositories and status:
[root@localhost ~]# yum repolist
Loaded plugins: fastestmirror, langpacks
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast
Determining fastest mirrors
* base: mirror.globo.com
* extras: mirror.turbozoneinternet.net.br
* updates: mirror.turbozoneinternet.net.br4 – All automatic updates, e.g. via yum-cron should be disabled:
[root@localhost ~]# systemctl status yum-cro
● yum-cron.service - Run automatic yum updates as a cron job
Loaded: loaded (/usr/lib/systemd/system/yum-cron.service; enabled; vendor preset: disabled)
Active: active (exited) since Sun 2021-03-07 14:35:54 -03; 8s ago
Process: 1936 ExecStart=/bin/touch /var/lock/subsys/yum-cron (code=exited, status=0/SUCCESS)
Main PID: 1936 (code=exited, status=0/SUCCESS)
Mar 07 14:35:54 localhost.localdomain systemd[1]: Starting Run automatic yum updates as a cron job...
Mar 07 14:35:54 localhost.localdomain systemd[1]: Started Run automatic yum updates as a cron job.
[root@localhost ~]# systemctl stop yum-cron.service
[root@localhost ~]# systemctl status yum-cron
● yum-cron.service - Run automatic yum updates as a cron job
Loaded: loaded (/usr/lib/systemd/system/yum-cron.service; enabled; vendor preset: disabled)
Active: inactive (dead) since Sun 2021-03-07 14:36:43 -03; 21s ago
Process: 1953 ExecStop=/bin/rm -f /var/lock/subsys/yum-cron (code=exited, status=0/SUCCESS)
Process: 1936 ExecStart=/bin/touch /var/lock/subsys/yum-cron (code=exited, status=0/SUCCESS)
Main PID: 1936 (code=exited, status=0/SUCCESS)
Mar 07 14:35:54 localhost.localdomain systemd[1]: Starting Run automatic yum updates as a cron job...
Mar 07 14:35:54 localhost.localdomain systemd[1]: Started Run automatic yum updates as a cron job.
Mar 07 14:36:43 localhost.localdomain systemd[1]: Stopping Run automatic yum updates as a cron job...
Mar 07 14:36:43 localhost.localdomain systemd[1]: Stopped Run automatic yum updates as a cron job.
[root@localhost ~]# systemctl disable yum-cron.service
Removed symlink /etc/systemd/system/multi-user.target.wants/yum-cron.service.
[root@localhost ~]#5 – Clear cache yum:
[root@localhost ~]# yum clean all
Loaded plugins: fastestmirror, langpacks
Cleaning repos: base extras updates
Cleaning up everything
Maybe you want: rm -rf /var/cache/yum, to also free up space taken by orphaned data from disabled or removed repos
Cleaning up list of fastest mirrors6 – Disable the repository permanently:
yum-config-manager --disable openlogic7 – Currently installed kernel:
[root@localhost ~]# grubby --info=ALL | grep ^kernel
kernel=/boot/vmlinuz-3.10.0-862.el7.x86_64
kernel=/boot/vmlinuz-0-rescue-f55da80029b04c21acdb1b9cffba6d48
[root@localhost ~]# uname -r
5.4.17-2136.300.7.el7uek.x86_648 – Download/create script centos2ol.sh:
[root@localhost ~]# vi centos2ol.sh
[root@localhost ~]# chmod 775 centos2ol.sh9 – Options for using the migration script:
Usage options
-r Reinstalls all CentOS RPMs with Oracle Linux RPMs
If a system is swiched to Oracle Linux and there is no newer Oracle Linux version of a package already installed then the CentOS version remains. This option proceeds to reinstall any CentOS RPM with an identical version from Oracle Linux. This is not necessary for support and has no impact to a systems functionality but is offered so a user can remove CentOS GPG keys from the truststore. A list of all non-Oracle RPMs will be displayed after the reinstall process.
-k Do not install the UEK kernel and disable UEK repos
This option will not install the UEK kernel and will disable all UEK yum repositories.
-V Verify RPM information before and after the switch
This option creates four output files in /var/tmp/:
${hostname}-rpms-list-[before|after].log: a sorted list of installed packages before and after the switch to Oracle Linux.
${hostname}-rpms-verified-[before|after].log: the RPM verification results for all installed packages before and after the switch to Oracle Linux.10 – Running the migration script:
[root@localhost ~]# ./centos2ol.sh -r -V
Checking for required packages...
Checking your distribution...
Creating a list of RPMs installed before the switch
Verifying RPMs installed before the switch against RPM database
package epel-release is not installed
Checking for yum lock...
Checking for required python packages...
Finding your repository directory...
Learning which repositories are enabled...
Repositories enabled before update include:
base
extras
updates11 – Final summary after the update:
Installed:
kernel-uek.x86_64 0:5.4.17-2036.103.3.1.el7uek
Complete!
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.4.17-2036.103.3.1.el7uek.x86_64
Found initrd image: /boot/initramfs-5.4.17-2036.103.3.1.el7uek.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1160.15.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1160.15.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-862.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-862.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-f55da80029b04c21acdb1b9cffba6d48
Found initrd image: /boot/initramfs-0-rescue-f55da80029b04c21acdb1b9cffba6d48.img
done
Removing yum cache
Creating a list of RPMs installed after the switch
Verifying RPMs installed after the switch against RPM database
Review the output of following files:
/var/tmp/localhost.localdomain-rpms-list-before.log
/var/tmp/localhost.localdomain-rpms-verified-before.log
/var/tmp/localhost.localdomain-rpms-list-after.log
/var/tmp/localhost.localdomain-rpms-verified-after.log
Switch complete. Oracle recommends rebooting this system.
12 – Restart the server and validate the migration, kernel installed after the change:
[root@localhost ~]# init 6
[root@localhost ~]# grubby --info=ALL | grep ^kernel
kernel=/boot/vmlinuz-5.4.17-2036.103.3.1.el7uek.x86_64
kernel=/boot/vmlinuz-3.10.0-1160.15.2.el7.x86_64
kernel=/boot/vmlinuz-3.10.0-862.el7.x86_64
kernel=/boot/vmlinuz-0-rescue-f55da80029b04c21acdb1b9cffba6d48 13 – Next, use grubby to verify that UEK is currently the default boot option:
[root@localhost ~]# grubby --default-kernel
/boot/vmlinuz-5.4.17-2036.103.3.1.el7uek.x86_64
[root@localhost ~]#14 – To replace the default kernel, you need to specify either the path to its vmlinuz file or its index. Use grubby to get that information for the replacement:
[root@localhost ~]# grubby --info /boot/vmlinuz-5.4.17-2036.103.3.1.el7uek.x86_64
index=0
kernel=/boot/vmlinuz-5.4.17-2036.103.3.1.el7uek.x86_64
args="ro crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet"
root=/dev/mapper/centos-root
initrd=/boot/initramfs-5.4.17-2036.103.3.1.el7uek.x86_64.img
title=Oracle Linux Server 7.9, with Unbreakable Enterprise Kernel 5.4.17-2036.103.3.1.el7uek.x86_64
15 – Final OS version:
[root@localhost ~]# cat /etc/*-release | grep PRETTY
PRETTY_NAME="Oracle Linux Server 7.9"16 -After migration confirm that the default kernel is UEK, if not install the Oracle UEK kernel:
[root@localhost ~]# uname -r
3.10.0-1160.42.2.el7.x86_64
[root@localhost ~]# yum install kernel-uek -y
[root@localhost ~]# init 6
# Kernel UEK
[root@localhost ~]# uname -r
5.4.17-2136.300.7.el7uek.x86_6417 – Disable non-Oracle Linux repositories:
[root@localhost ~]# yum repolist
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
* epel: d2lzkl7pfhq30w.cloudfront.net
repo id repo name status
epel/x86_64 Extra Packages for Enterprise Linux 7 - x86_64 13,683
ol7_UEKR6/x86_64 Latest Unbreakable Enterprise Kernel Release 6 for Oracle Linux 7Server (x86_64) 456
ol7_latest/x86_64 Oracle Linux 7Server Latest (x86_64) 23,278
ol7_optional_latest/x86_64 Oracle Linux 7Server Optional Latest (x86_64) 16,543
repolist: 53,960
[root@localhost ~]# yum-config-manager --disable epel
[root@localhost ~]# yum repolist
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
repo id repo name status
ol7_UEKR6/x86_64 Latest Unbreakable Enterprise Kernel Release 6 for Oracle Linux 7Server (x86_64) 456
ol7_latest/x86_64 Oracle Linux 7Server Latest (x86_64) 23,278
ol7_optional_latest/x86_64 Oracle Linux 7Server Optional Latest (x86_64) 16,543
repolist: 40,27718 – Update the Operating System:
[root@localhost ~]# yum update19 – Links:
https://www.oracle.com/br/linux/
https://blogs.oracle.com/scoter/switch-from-centos-to-oracle-linux-example
https://linux.oracle.com/switch/centos/
https://github.com/oracle/centos2ol
https://github.com/oracle/centos2ol/blob/main/centos2ol.sh