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How to switch from RHCK kernel to UEKR7 on OL8

  • Updated
  • Products: FlashGrid Cluster on Azure
  • Products: FlashGrid Storage Fabric
  • Products: FlashGrid Cluster on AWS

FlashGrid Cluster deployed with Oracle Linux 8 (prior to FlashGrid 22.06 release) will have only Red Hat Compatible Kernel (RHCK) installed. This article provides instructions for switching to UEKR7 kernel after a cluster is deployed.

To switch the RHCK kernel to UEKR7, repeat the following steps on each node, one node at a time:

  1. edit /etc/dnf/dnf.conf file and comment out or remove the following line: 
    exclude=kernel-uek*
  2. disable UEKR6 yum channel 
    yum config-manager --set-disabled ol8_UEKR6
  3. enable UEKR7 yum channel 
    yum config-manager --set-enabled ol8_UEKR7

  4. re-check the yum configuration to verify UEKR7 yum channel is properly enabled, and there is no UEKR6 yum channel in the output

    yum repolist

    (example output):

    [root@rac1 ~]# yum repolist
repo id                       repo name
ol8_UEKR7                     Latest Unbreakable Enterprise Kernel Release 7 for Oracle Linux 8 (x86_64)
ol8_appstream                 Oracle Linux 8 Application Stream (x86_64)
ol8_baseos_latest             Oracle Linux 8 BaseOS Latest (x86_64)
packages-microsoft-com-prod   packages-microsoft-com-prod
  5. install required UEK packages 
    yum install kernel-uek kernel-uek-core kernel-uek-devel kernel-uek-modules kernel-uek-modules-extra

  6. get info on all kernels installed

    grubby --info=ALL | grep ^kernel=

    (example output):

    [root@rac1 ~]# grubby --info=ALL | grep ^kernel=
kernel="/boot/vmlinuz-4.18.0-348.7.1.el8_5.x86_64"
kernel="/boot/vmlinuz-0-rescue-74eba1c7c8fc440780d870f8e26c64b9"
kernel="/boot/vmlinuz-5.15.0-309.180.4.el8uek.x86_64"
kernel="/boot/vmlinuz-4.18.0-305.25.1.el8_4.x86_64"

  7. check the default kernel

    grubby --default-kernel

    (example output):

    [root@rac1 ~]# grubby --default-kernel
    /boot/vmlinuz-5.15.0-309.180.4.el8uek.x86_64
  8. in case the UEKR7 kernel 5.15.0-* is not default, it needs to be set (substitute the UEKR7 kernel from step 6): 
    grubby --set-default=/boot/vmlinuz-5.15.0-309.180.4.el8uek.x86_64
  9. confirm the default kernel to make sure that it has been changed properly 
    grubby --default-kernel
  10. Reboot the node
  11. Before repeating the steps on the next node, wait until the node boots up, all disks are back online, and resyncing operations are complete on all disk groups. All disk groups must have zero offline disks and Resync = No before it is safe to update the next node. Check the status using the following command: 
    flashgrid-cluster

Note:

In case the scope of switching the kernel to UEKR7 is to use with ACFS/ADVM, the steps specified in How To Install/Reinstall Or Deinstall ACFS Modules/Installation Manually? (Doc ID 1371067.1) must be followed.

References:

Oracle Linux: How to Change Default Kernel on GRUB2 Using the grubby Tool (Doc ID 2605359.1)

ACFS Support On OS Platforms (Certification Matrix) (Doc ID 1369107.1)

How To Install/Reinstall Or Deinstall ACFS Modules/Installation Manually? (Doc ID 1371067.1)