Update DRBD kernel module after a node has rebooted into a new kernel

If a node was rebooted to a new OS kernel level and the DRBD kernel module is now incompatible with the current OS kernel level then RDQM might fail to start correctly on the node.

About this task

For example, if a node was rebooted into a RHEL 7.8 (3.10.0_1127) kernel with a RHEL 7.7 (3.10.0_1062) DRBD kernel module installed (for example, kmod-drbd-9.0.23_3.10.0_1062-1.x86_64), RDQM does not start. The command rdqmstatus -m qmname shows an HA status of Unknown for an HA or DR/HA queue manager, and a DR status of Unknown for a DR queue manager.

The queue manager will not run on this node until the issue is resolved.

The running kernel can be displayed by using the following command:

$ uname -r
3.10.0-1127.13.1.el7.x86_64

And the installed DRBD kernel module can be displayed by using the following command:

$ rpm -qa | grep kmod-drbd
kmod-drbd-9.0.23_3.10.0_1062-1.x86_64

To recover from this situation, complete the following procedure in turn on each node that has been rebooted into a new kernel.

Procedure

Log in as root, or with sufficient authority to run the following commands.

You can do this by adding sudo before the commands, or by changing to the root user in the shell with the su command. For more information, see Exploring the differences between sudo and su commands in Linux®.
Determine which DRBD kernel module is now needed for the system. Seehttps://ibm.biz/mqrdqmkernelmods for up-to-date kernel module information. Helper scripts are provided in the kmod-drbd-9 directories. For example, on a RHEL 7.8 system, running the helper script kmod-drbd-9/modver returns the following information, identifying the kernel module that you need to install:
```
kmod-drbd-9.0.23_3.10.0_1127-1.x86_64.rpm
```
Update the DRBD kernel module to the one that you identified in step 2. For example:
```
yum install kmod-drbd-9.0.23_3.10.0_1127-1.x86_64.rpm
```
Reboot the node:
```
sudo reboot
```