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| 1 | +// Module included in the following assemblies: |
| 2 | +// |
| 3 | +// * installing/installing_bibm_power/installing-ibm-power.adoc |
| 4 | +// * installing/installing_ibm_power/installing-restricted-networks-ibm-power.adoc |
| 5 | + |
| 6 | +[id="rhcos-enabling-multipathday-1-power_{context}"] |
| 7 | += Enabling multipathing with kernel arguments on {op-system} |
| 8 | + |
| 9 | +In {product-title} 4.9 or later, during installation, you can enable multipathing for provisioned nodes. {op-system} supports multipathing on the primary disk. Multipathing provides added benefits of stronger resilience to hardware failure to achieve higher host availability. |
| 10 | + |
| 11 | +During the initial cluster creation, you might want to add kernel arguments to all master or worker nodes. To add kernel arguments to master or worker nodes, you can create a `MachineConfig` object and inject that object into the set of manifest files used by Ignition during cluster setup. |
| 12 | + |
| 13 | +.Procedure |
| 14 | + |
| 15 | +. Change to the directory that contains the installation program and generate the Kubernetes manifests for the cluster: |
| 16 | ++ |
| 17 | +[source,terminal] |
| 18 | +---- |
| 19 | +$ ./openshift-install create manifests --dir=<installation_directory> |
| 20 | +---- |
| 21 | + |
| 22 | +. Decide if you want to add kernel arguments to worker or master nodes. |
| 23 | + |
| 24 | +* Create a machine config file. For example, create a `99-master-kargs-mpath.yaml` that instructs the cluster to add the `master` label and identify the multipath kernel argument: |
| 25 | ++ |
| 26 | +[source,yaml] |
| 27 | +---- |
| 28 | +apiVersion: machineconfiguration.openshift.io/v1 |
| 29 | +kind: MachineConfig |
| 30 | +metadata: |
| 31 | + labels: |
| 32 | + machineconfiguration.openshift.io/role: "master" |
| 33 | + name: 99-master-kargs-mpath |
| 34 | +spec: |
| 35 | + kernelArguments: |
| 36 | + - 'rd.multipath=default' |
| 37 | + - 'root=/dev/disk/by-label/dm-mpath-root' |
| 38 | +---- |
| 39 | + |
| 40 | +. To enable multipathing post-installation on worker nodes: |
| 41 | + |
| 42 | +* Create a machine config file. For example, create a `99-worker-kargs-mpath.yaml` that instructs the cluster to add the `worker` label and identify the multipath kernel argument: |
| 43 | ++ |
| 44 | +[source,yaml] |
| 45 | +---- |
| 46 | +apiVersion: machineconfiguration.openshift.io/v1 |
| 47 | +kind: MachineConfig |
| 48 | +metadata: |
| 49 | + labels: |
| 50 | + machineconfiguration.openshift.io/role: "worker" |
| 51 | + name: 99-worker-kargs-mpath |
| 52 | +spec: |
| 53 | + kernelArguments: |
| 54 | + - 'rd.multipath=default' |
| 55 | + - 'root=/dev/disk/by-label/dm-mpath-root' |
| 56 | +---- |
| 57 | ++ |
| 58 | +You can now continue on to create the cluster. |
| 59 | + |
| 60 | +[IMPORTANT] |
| 61 | +==== |
| 62 | +Additional post-installation steps are required to fully enable multipathing. For more information, see “Enabling multipathing with kernel arguments on {op-system}" in _Post-installation machine configuration tasks_. |
| 63 | +==== |
| 64 | + |
| 65 | +In case of MPIO failure, use the bootlist command to update the boot device list with alternate logical device names. |
| 66 | +The command displays a boot list and it designates the possible boot devices for when the system is booted in normal mode. |
| 67 | + |
| 68 | +.. To display a boot list and specify the possible boot devices if the system is booted in normal mode, enter the following command: |
| 69 | ++ |
| 70 | +[source,terminal] |
| 71 | +---- |
| 72 | +$ bootlist -m normal -o |
| 73 | +sda |
| 74 | +---- |
| 75 | +.. To update the boot list for normal mode and add alternate device names, enter the following command: |
| 76 | ++ |
| 77 | +[source,terminal] |
| 78 | +---- |
| 79 | +$ bootlist -m normal -o /dev/sdc /dev/sdd /dev/sde |
| 80 | +sdc |
| 81 | +sdd |
| 82 | +sde |
| 83 | +---- |
| 84 | ++ |
| 85 | +If the original boot disk path is down, the node reboots from the alternate device registered in the normal boot device list. |
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