How to switch from UEKR6 kernel to UEKR7 on OL8 – FlashGrid Help Center

FlashGrid Cluster deployed with Oracle Linux 8 (from FlashGrid 22.06 to 24.11 releases) will only have UEKR6 kernel installed. Starting with FlashGrid 25.05, UEKR7 is used by default. This article provides instructions for switching from UEKR6 to UEKR7 kernel after a cluster is deployed.

Prerequisites

(ACFS only): if ACFS is in use, ensure that the target UEKR7 kernel is supported by the installed Grid Infrastructure Release Update: ACFS and AFD Support On OS Platforms (Certification Matrix). (Doc ID 1369107.1). In case it is not supported, update Grid Infrastructure first on all cluster nodes before switching the kernel.

Switch UEKR6 kernel to UEKR7

To switch the UEKR6 kernel to UEKR7, repeat the following steps on each node, one node at a time:

Disable UEKR6 yum channel:

# yum config-manager --set-disabled ol8_UEKR6

Enable UEKR7 yum channel:

# yum config-manager --set-enabled ol8_UEKR7

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

Sample 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

Install required UEK RPMs:

# yum install kernel-uek kernel-uek-core kernel-uek-devel kernel-uek-modules kernel-uek-modules-extra

Get info on all kernels installed:

# grubby --info=ALL | grep ^kernel=

Sample output:

[root@rac1 ~]# grubby --info=ALL | grep ^kernel=
kernel="/boot/vmlinuz-5.15.0-309.180.4.el8uek.x86_64"
kernel="/boot/vmlinuz-5.4.17-2136.335.4.el8uek.x86_64"
kernel="/boot/vmlinuz-4.18.0-553.22.1.el8_10.x86_64"
kernel="/boot/vmlinuz-0-rescue-e71d1c91e4fc425fa3ccf343448ef7b1"

Check the default kernel:

# grubby --default-kernel

Sample output:

[root@rac1 ~]# grubby --default-kernel
/boot/vmlinuz-5.15.0-309.180.4.el8uek.x86_64

In case the UEKR7 kernel 5.15.0-* is not default, it needs to be set (substitute the UEKR7 kernel from step 5):
```
# grubby --set-default=/boot/vmlinuz-5.15.0-309.180.4.el8uek.x86_64
```
Confirm the default kernel to make sure that it has been changed properly:
```
# grubby --default-kernel
```
Reboot the node
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
```