Chapter 4. Configuring a Red Hat High Availability cluster on Microsoft Azure

Procedure

1. Authenticate your system with Azure and log in.

   $ az login

   Note

   If a browser is available in your environment, the CLI opens your browser to the Azure sign-in page.

   Example:

   [clouduser@localhost]$ az login
   
   To sign in, use a web browser to open the page https://aka.ms/devicelogin and enter the code FDMSCMETZ to authenticate.
     [
       {
         "cloudName": "AzureCloud",
         "id": "Subscription ID",
         "isDefault": true,
         "name": "MySubscriptionName",
         "state": "Enabled",
         "tenantId": "Tenant ID",
         "user": {
           "name": "clouduser@company.com",
           "type": "user"
         }
       }
     ]

2. Create a resource group in an Azure region.

   $ az group create --name resource-group --location azure-region

   Example:

   [clouduser@localhost]$ az group create --name azrhelclirsgrp --location southcentralus
   
   {
     "id": "/subscriptions//resourceGroups/azrhelclirsgrp",
     "location": "southcentralus",
     "managedBy": null,
     "name": "azrhelclirsgrp",
     "properties": {
       "provisioningState": "Succeeded"
     },
     "tags": null
   }

3. Create a storage account.

   $ az storage account create -l azure-region -n storage-account-name -g resource-group --sku sku_type --kind StorageV2

   Example:

   [clouduser@localhost]$ az storage account create -l southcentralus -n azrhelclistact -g azrhelclirsgrp --sku Standard_LRS --kind StorageV2
   
   {
     "accessTier": null,
     "creationTime": "2017-04-05T19:10:29.855470+00:00",
     "customDomain": null,
     "encryption": null,
     "id": "/subscriptions//resourceGroups/azrhelclirsgrp/providers/Microsoft.Storage/storageAccounts/azrhelclistact",
     "kind": "StorageV2",
     "lastGeoFailoverTime": null,
     "location": "southcentralus",
     "name": "azrhelclistact",
     "primaryEndpoints": {
       "blob": "https://azrhelclistact.blob.core.windows.net/",
       "file": "https://azrhelclistact.file.core.windows.net/",
       "queue": "https://azrhelclistact.queue.core.windows.net/",
       "table": "https://azrhelclistact.table.core.windows.net/"
   },
   "primaryLocation": "southcentralus",
   "provisioningState": "Succeeded",
   "resourceGroup": "azrhelclirsgrp",
   "secondaryEndpoints": null,
   "secondaryLocation": null,
   "sku": {
     "name": "Standard_LRS",
     "tier": "Standard"
   },
   "statusOfPrimary": "available",
   "statusOfSecondary": null,
   "tags": {},
     "type": "Microsoft.Storage/storageAccounts"
   }

4. Get the storage account connection string.

   $ az storage account show-connection-string -n storage-account-name -g resource-group

   Example:

   [clouduser@localhost]$ az storage account show-connection-string -n azrhelclistact -g azrhelclirsgrp
   {
     "connectionString": "DefaultEndpointsProtocol=https;EndpointSuffix=core.windows.net;AccountName=azrhelclistact;AccountKey=NreGk...=="
   }

5. Export the connection string by copying the connection string and pasting it into the following command. This string connects your system to the storage account.

   $ export AZURE_STORAGE_CONNECTION_STRING="storage-connection-string"

   Example:

   [clouduser@localhost]$ export AZURE_STORAGE_CONNECTION_STRING="DefaultEndpointsProtocol=https;EndpointSuffix=core.windows.net;AccountName=azrhelclistact;AccountKey=NreGk...=="

6. Create the storage container.

   $ az storage container create -n container-name

   Example:

   [clouduser@localhost]$ az storage container create -n azrhelclistcont
   
   {
     "created": true
   }

7. Create a virtual network. All cluster nodes must be in the same virtual network.

   $ az network vnet create -g resource group --name vnet-name --subnet-name subnet-name

   Example:

   [clouduser@localhost]$ az network vnet create --resource-group azrhelclirsgrp --name azrhelclivnet1 --subnet-name azrhelclisubnet1
   {
     "newVNet": {
       "addressSpace": {
         "addressPrefixes": [
         "10.0.0.0/16"
         ]
     },
     "dhcpOptions": {
       "dnsServers": []
     },
     "etag": "W/\"\"",
     "id": "/subscriptions//resourceGroups/azrhelclirsgrp/providers/Microsoft.Network/virtualNetworks/azrhelclivnet1",
     "location": "southcentralus",
     "name": "azrhelclivnet1",
     "provisioningState": "Succeeded",
     "resourceGroup": "azrhelclirsgrp",
     "resourceGuid": "0f25efee-e2a6-4abe-a4e9-817061ee1e79",
     "subnets": [
       {
         "addressPrefix": "10.0.0.0/24",
         "etag": "W/\"\"",
         "id": "/subscriptions//resourceGroups/azrhelclirsgrp/providers/Microsoft.Network/virtualNetworks/azrhelclivnet1/subnets/azrhelclisubnet1",
         "ipConfigurations": null,
         "name": "azrhelclisubnet1",
         "networkSecurityGroup": null,
         "provisioningState": "Succeeded",
         "resourceGroup": "azrhelclirsgrp",
         "resourceNavigationLinks": null,
         "routeTable": null
       }
     ],
     "tags": {},
     "type": "Microsoft.Network/virtualNetworks",
     "virtualNetworkPeerings": null
     }
   }

8. Create an availability set. All cluster nodes must be in the same availability set.

   $ az vm availability-set create --name MyAvailabilitySet --resource-group MyResourceGroup

   Example:

   [clouduser@localhost]$ az vm availability-set create --name rhelha-avset1 --resource-group azrhelclirsgrp
   {
     "additionalProperties": {},
       "id": "/subscriptions/.../resourceGroups/azrhelclirsgrp/providers/Microsoft.Compute/availabilitySets/rhelha-avset1",
       "location": "southcentralus",
       "name": “rhelha-avset1",
       "platformFaultDomainCount": 2,
       "platformUpdateDomainCount": 5,
   
   [omitted]

Procedure

1. Enter the following grep command to determine if the required Hyper-V device drivers are installed.

   # lsinitrd | grep hv

   In the example below, all required drivers are installed.

   # lsinitrd | grep hv
   drwxr-xr-x   2 root     root            0 Aug 12 14:21 usr/lib/modules/3.10.0-932.el8.x86_64/kernel/drivers/hv
   -rw-r--r--   1 root     root        31272 Aug 11 08:45 usr/lib/modules/3.10.0-932.el8.x86_64/kernel/drivers/hv/hv_vmbus.ko.xz
   -rw-r--r--   1 root     root        25132 Aug 11 08:46 usr/lib/modules/3.10.0-932.el8.x86_64/kernel/drivers/net/hyperv/hv_netvsc.ko.xz
   -rw-r--r--   1 root     root         9796 Aug 11 08:45 usr/lib/modules/3.10.0-932.el8.x86_64/kernel/drivers/scsi/hv_storvsc.ko.xz

   If all the drivers are not installed, complete the remaining steps.

   Note

   An hv_vmbus driver may exist in the environment. Even if this driver is present, complete the following steps.

2. Create a file named hv.conf in /etc/dracut.conf.d.

3. Add the following driver parameters to the hv.conf file.

   add_drivers+=" hv_vmbus "
   add_drivers+=" hv_netvsc "
   add_drivers+=" hv_storvsc "
   add_drivers+=" nvme "

   Note

   Note the spaces before and after the quotes, for example, add_drivers+=" hv_vmbus ". This ensures that unique drivers are loaded in the event that other Hyper-V drivers already exist in the environment.

4. Regenerate the initramfs image.

   # dracut -f -v --regenerate-all

Verification

1. Reboot the machine.
2. Run the lsinitrd | grep hv command to verify that the drivers are installed.

Procedure

1. Log in to the VM.

2. Register the VM, and enable the Red Hat Enterprise Linux 8 repository.

   # subscription-manager register --auto-attach
   Installed Product Current Status:
   Product Name: Red Hat Enterprise Linux for x86_64
   Status: Subscribed

3. Ensure that the cloud-init and hyperv-daemons packages are installed.

   # yum install cloud-init hyperv-daemons -y

4. Create cloud-init configuration files that are needed for integration with Azure services:

   1. To enable logging to the Hyper-V Data Exchange Service (KVP), create the /etc/cloud/cloud.cfg.d/10-azure-kvp.cfg configuration file and add the following lines to that file.

      reporting:
          logging:
              type: log
          telemetry:
              type: hyperv

   2. To add Azure as a datasource, create the /etc/cloud/cloud.cfg.d/91-azure_datasource.cfg configuration file, and add the following lines to that file.

      datasource_list: [ Azure ]
      datasource:
          Azure:
              apply_network_config: False

5. To ensure that specific kernel modules are blocked from loading automatically, edit or create the /etc/modprobe.d/blocklist.conf file and add the following lines to that file.

   blacklist nouveau
   blacklist lbm-nouveau
   blacklist floppy
   blacklist amdgpu
   blacklist skx_edac
   blacklist intel_cstate

6. Modify udev network device rules:

   1. Remove the following persistent network device rules if present.

      # rm -f /etc/udev/rules.d/70-persistent-net.rules
      # rm -f /etc/udev/rules.d/75-persistent-net-generator.rules
      # rm -f /etc/udev/rules.d/80-net-name-slot-rules

   2. To ensure that Accelerated Networking on Azure works as intended, create a new network device rule /etc/udev/rules.d/68-azure-sriov-nm-unmanaged.rules and add the following line to it.

      SUBSYSTEM=="net", DRIVERS=="hv_pci", ACTION=="add", ENV{NM_UNMANAGED}="1"

7. Set the sshd service to start automatically.

   # systemctl enable sshd
   # systemctl is-enabled sshd

8. Modify kernel boot parameters:

   1. Open the /etc/default/grub file, and ensure the GRUB_TIMEOUT line has the following value.

      GRUB_TIMEOUT=10

   2. Remove the following options from the end of the GRUB_CMDLINE_LINUX line if present.

      rhgb quiet

   3. Ensure the /etc/default/grub file contains the following lines with all the specified options.

      GRUB_CMDLINE_LINUX="loglevel=3 crashkernel=auto console=tty1 console=ttyS0 earlyprintk=ttyS0 rootdelay=300"
      GRUB_TIMEOUT_STYLE=countdown
      GRUB_TERMINAL="serial console"
      GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

      Note

      If you do not plan to run your workloads on HDDs, add elevator=none to the end of the GRUB_CMDLINE_LINUX line.

      This sets the I/O scheduler to none, which improves I/O performance when running workloads on SSDs.

   4. Regenerate the grub.cfg file.

      • On a BIOS-based machine:

        # grub2-mkconfig -o /boot/grub2/grub.cfg

      • On a UEFI-based machine:

        # grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

        If your system uses a non-default location for grub.cfg, adjust the command accordingly.

9. Configure the Windows Azure Linux Agent (WALinuxAgent):

   1. Install and enable the WALinuxAgent package.

      # yum install WALinuxAgent -y
      # systemctl enable waagent

   2. To ensure that a swap partition is not used in provisioned VMs, edit the following lines in the /etc/waagent.conf file.

      Provisioning.DeleteRootPassword=y
      ResourceDisk.Format=n
      ResourceDisk.EnableSwap=n

10. Prepare the VM for Azure provisioning:

    1. Unregister the VM from Red Hat Subscription Manager.

       # subscription-manager unregister

    2. Clean up the existing provisioning details.

       # waagent -force -deprovision

       Note

       This command generates warnings, which are expected because Azure handles the provisioning of VMs automatically.

    3. Clean the shell history and shut down the VM.

       # export HISTSIZE=0
       # poweroff

Procedure

1. On any node in the HA cluster, log in to your Azure account.

   $ az login

2. Create a json configuration file for a custom role for the Azure fence agent. Use the following configuration, but replace <subscription-id> with your subscription IDs.

   {
         "Name": "Linux Fence Agent Role",
         "description": "Allows to power-off and start virtual machines",
         "assignableScopes": [
                 "/subscriptions/<subscription-id>"
         ],
         "actions": [
                 "Microsoft.Compute/*/read",
                 "Microsoft.Compute/virtualMachines/powerOff/action",
                 "Microsoft.Compute/virtualMachines/start/action"
         ],
         "notActions": [],
         "dataActions": [],
         "notDataActions": []
   }

3. Define the custom role for the Azure fence agent. Use the json file created in the previous step to do this.

   $ az role definition create --role-definition azure-fence-role.json
   
   {
     "assignableScopes": [
       "/subscriptions/<my-subscription-id>"
     ],
     "description": "Allows to power-off and start virtual machines",
     "id": "/subscriptions/<my-subscription-id>/providers/Microsoft.Authorization/roleDefinitions/<role-id>",
     "name": "<role-id>",
     "permissions": [
       {
         "actions": [
           "Microsoft.Compute/*/read",
           "Microsoft.Compute/virtualMachines/powerOff/action",
           "Microsoft.Compute/virtualMachines/start/action"
         ],
         "dataActions": [],
         "notActions": [],
         "notDataActions": []
       }
     ],
     "roleName": "Linux Fence Agent Role",
     "roleType": "CustomRole",
     "type": "Microsoft.Authorization/roleDefinitions"
   }

4. In the Azure web console interface, select Virtual Machine Click Identity in the left-side menu.
5. Select On Click Save click Yes to confirm.
6. Click Azure role assignments Add role assignment.
7. Select the Scope required for the role, for example Resource Group.
8. Select the required Resource Group.
9. Optional: Change the Subscription if necessary.
10. Select the Linux Fence Agent Role role.
11. Click Save.

Procedure

1. Convert the image from qcow2 to raw format.

   $ qemu-img convert -f qcow2 -O raw <image-name>.qcow2 <image-name>.raw

2. Create a shell script with the following content.

   #!/bin/bash
   MB=$((1024 * 1024))
   size=$(qemu-img info -f raw --output json "$1" | gawk 'match($0, /"virtual-size": ([0-9]+),/, val) {print val[1]}')
   rounded_size=$((($size/$MB + 1) * $MB))
   if [ $(($size % $MB)) -eq  0 ]
   then
    echo "Your image is already aligned. You do not need to resize."
    exit 1
   fi
   echo "rounded size = $rounded_size"
   export rounded_size

3. Run the script. This example uses the name align.sh.

   $ sh align.sh <image-xxx>.raw

   • If the message "Your image is already aligned. You do not need to resize." displays, proceed to the following step.
   • If a value displays, your image is not aligned.

4. Use the following command to convert the file to a fixed VHD format.

   The sample uses qemu-img version 2.12.0.

   $ qemu-img convert -f raw -o subformat=fixed,force_size -O vpc <image-xxx>.raw <image.xxx>.vhd

   Once converted, the VHD file is ready to upload to Azure.

5. If the raw image is not aligned, complete the following steps to align it.

   1. Resize the raw file by using the rounded value displayed when you ran the verification script.

      $ qemu-img resize -f raw <image-xxx>.raw <rounded-value>

   2. Convert the raw image file to a VHD format.

      The sample uses qemu-img version 2.12.0.

      $ qemu-img convert -f raw -o subformat=fixed,force_size -O vpc <image-xxx>.raw <image.xxx>.vhd

      Once converted, the VHD file is ready to upload to Azure.

Procedure

1. Upload the VHD file to the storage container. It may take several minutes. To get a list of storage containers, enter the az storage container list command.

   $ az storage blob upload \
       --account-name <storage-account-name> --container-name <container-name> \
       --type page --file <path-to-vhd> --name <image-name>.vhd

   Example:

   [clouduser@localhost]$ az storage blob upload \
   --account-name azrhelclistact --container-name azrhelclistcont \
   --type page --file rhel-image-{ProductNumber}.vhd --name rhel-image-{ProductNumber}.vhd
   
   Percent complete: %100.0

2. Get the URL for the uploaded VHD file to use in the following step.

   $ az storage blob url -c <container-name> -n <image-name>.vhd

   Example:

   $ az storage blob url -c azrhelclistcont -n rhel-image-8.vhd "https://azrhelclistact.blob.core.windows.net/azrhelclistcont/rhel-image-8.vhd"

3. Create the Azure custom image.

   $ az image create -n <image-name> -g <resource-group> -l <azure-region> --source <URL> --os-type linux

   Note

   The default hypervisor generation of the VM is V1. You can optionally specify a V2 hypervisor generation by including the option --hyper-v-generation V2. Generation 2 VMs use a UEFI-based boot architecture. See Support for generation 2 VMs on Azure for information about generation 2 VMs.

   The command may return the error "Only blobs formatted as VHDs can be imported." This error may mean that the image was not aligned to the nearest 1 MB boundary before it was converted to VHD.

   Example:

   $ az image create -n rhel8 -g azrhelclirsgrp2 -l southcentralus --source https://azrhelclistact.blob.core.windows.net/azrhelclistcont/rhel-image-8.vhd --os-type linux

Procedure

1. Launch an SSH terminal session and connect to the VM by using the administrator name and public IP address.

   $ ssh administrator@PublicIP

   To get the public IP address for an Azure VM, open the VM properties in the Azure Portal or enter the following Azure CLI command.

   $ az vm list -g <resource-group> -d --output table

   Example:

   [clouduser@localhost ~] $ az vm list -g azrhelclirsgrp -d --output table
   Name    ResourceGroup           PowerState      PublicIps        Location
   ------  ----------------------  --------------  -------------    --------------
   node01  azrhelclirsgrp          VM running      192.98.152.251    southcentralus

2. Register the VM with Red Hat.

   $ sudo -i
   # subscription-manager register --auto-attach

   Note

   If the --auto-attach command fails, manually register the VM to your subscription.

3. Disable all repositories.

   # subscription-manager repos --disable=*

4. Enable the RHEL 8 Server HA repositories.

   # subscription-manager repos --enable=rhel-8-for-x86_64-highavailability-rpms

5. Update all packages.

   # yum update -y

6. Install the Red Hat High Availability Add-On software packages, along with the Azure fencing agent from the High Availability channel.

   # yum install pcs pacemaker fence-agents-azure-arm

7. The user hacluster was created during the pcs and pacemaker installation in the previous step. Create a password for hacluster on all cluster nodes. Use the same password for all nodes.

   # passwd hacluster

8. Add the high availability service to the RHEL Firewall if firewalld.service is installed.

   # firewall-cmd --permanent --add-service=high-availability
   # firewall-cmd --reload

9. Start the pcs service and enable it to start on boot.

   # systemctl start pcsd.service
   # systemctl enable pcsd.service
   
   Created symlink from /etc/systemd/system/multi-user.target.wants/pcsd.service to /usr/lib/systemd/system/pcsd.service.

Procedure

1. On one of the nodes, enter the following command to authenticate the pcs user hacluster. In the command, specify the name of each node in the cluster.

   # pcs host auth <hostname1> <hostname2> <hostname3>

   Example:

   [root@node01 clouduser]# pcs host auth node01 node02 node03
   Username: hacluster
   Password:
   node01: Authorized
   node02: Authorized
   node03: Authorized

2. Create the cluster.

   # pcs cluster setup <cluster_name> <hostname1> <hostname2> <hostname3>

   Example:

   [root@node01 clouduser]# pcs cluster setup new_cluster node01 node02 node03
   
   [...]
   
   Synchronizing pcsd certificates on nodes node01, node02, node03...
   node02: Success
   node03: Success
   node01: Success
   Restarting pcsd on the nodes in order to reload the certificates...
   node02: Success
   node03: Success
   node01: Success

Verification

1. Enable the cluster.

   [root@node01 clouduser]# pcs cluster enable --all
   node02: Cluster Enabled
   node03: Cluster Enabled
   node01: Cluster Enabled

2. Start the cluster.

   [root@node01 clouduser]# pcs cluster start --all
   node02: Starting Cluster...
   node03: Starting Cluster...
   node01: Starting Cluster...

Procedure

1. Identify the Azure node name for each RHEL VM. You use the Azure node names to configure the fence device.

   # fence_azure_arm \
       -l <AD-Application-ID> -p <AD-Password> \
       --resourceGroup <MyResourceGroup> --tenantId <Tenant-ID> \
       --subscriptionId <Subscription-ID> -o list

   Example:

   [root@node01 clouduser]# fence_azure_arm \
   -l e04a6a49-9f00-xxxx-xxxx-a8bdda4af447 -p z/a05AwCN0IzAjVwXXXXXXXEWIoeVp0xg7QT//JE=
   --resourceGroup azrhelclirsgrp --tenantId 77ecefb6-cff0-XXXX-XXXX-757XXXX9485
   --subscriptionId XXXXXXXX-38b4-4527-XXXX-012d49dfc02c -o list
   
   node01,
   node02,
   node03,

2. View the options for the Azure ARM STONITH agent.

   # pcs stonith describe fence_azure_arm

   Example:

   # pcs stonith describe fence_apc
   Stonith options:
   password: Authentication key
   password_script: Script to run to retrieve password

   Warning

   For fence agents that provide a method option, do not specify a value of cycle as it is not supported and can cause data corruption.

   Some fence devices can fence only a single node, while other devices can fence multiple nodes. The parameters you specify when you create a fencing device depend on what your fencing device supports and requires.

   You can use the pcmk_host_list parameter when creating a fencing device to specify all of the machines that are controlled by that fencing device.

   You can use pcmk_host_map parameter when creating a fencing device to map host names to the specifications that comprehends the fence device.

3. Create a fence device.

   # pcs stonith create clusterfence fence_azure_arm

Verification

1. Test the fencing agent for one of the other nodes.

   # pcs stonith fence azurenodename

   Example:

   [root@node01 clouduser]# pcs status
   Cluster name: newcluster
   Stack: corosync
   Current DC: node01 (version 1.1.18-11.el7-2b07d5c5a9) - partition with quorum
   Last updated: Fri Feb 23 11:44:35 2018
   Last change: Fri Feb 23 11:21:01 2018 by root via cibadmin on node01
   
   3 nodes configured
   1 resource configured
   
   Online: [ node01 node03 ]
   OFFLINE: [ node02 ]
   
   Full list of resources:
   
     clusterfence  (stonith:fence_azure_arm):  Started node01
   
   Daemon Status:
     corosync: active/disabled
     pacemaker: active/disabled
     pcsd: active/enabled

2. Start the node that was fenced in the previous step.

   # pcs cluster start <hostname>

3. Check the status to verify the node started.

   # pcs status

   Example:

   [root@node01 clouduser]# pcs status
   Cluster name: newcluster
   Stack: corosync
   Current DC: node01 (version 1.1.18-11.el7-2b07d5c5a9) - partition with quorum
   Last updated: Fri Feb 23 11:34:59 2018
   Last change: Fri Feb 23 11:21:01 2018 by root via cibadmin on node01
   
   3 nodes configured
   1 resource configured
   
   Online: [ node01 node02 node03 ]
   
   Full list of resources:
   
   clusterfence    (stonith:fence_azure_arm):  Started node01
   
   Daemon Status:
     corosync: active/disabled
     pacemaker: active/disabled
     pcsd: active/enabled

Procedure

1. Create a Basic load balancer. Select Internal load balancer, the Basic SKU, and Dynamic for the type of IP address assignment.
2. Create a back-end address pool. Associate the backend pool to the availability set created while creating Azure resources in HA. Do not set any target network IP configurations.
3. Create a health probe. For the health probe, select TCP and enter port 61000. You can use TCP port number that does not interfere with another service. For certain HA product applications (for example, SAP HANA and SQL Server), you may need to work with Microsoft to identify the correct port to use.
4. Create a load balancer rule. To create the load balancing rule, the default values are prepopulated. Ensure to set Floating IP (direct server return) to Enabled.

Procedure

1. Install the nmap-ncat resource agents on all nodes.

   # yum install nmap-ncat resource-agents

   Perform the following steps on a single node.

2. Create the pcs resources and group. Use your load balancer FrontendIP for the IPaddr2 address.

   # pcs resource create resource-name IPaddr2 ip="10.0.0.7" --group cluster-resources-group

3. Configure the load balancer resource agent.

   # pcs resource create resource-loadbalancer-name azure-lb port=port-number --group cluster-resources-group

Procedure

1. Create a shared block volume by using the Azure command az disk create.

   $ az disk create -g <resource_group> -n <shared_block_volume_name> --size-gb <disk_size> --max-shares <number_vms> -l <location>

   For example, the following command creates a shared block volume named shared-block-volume.vhd in the resource group sharedblock within the Azure Availability Zone westcentralus.

   $ az disk create -g sharedblock-rg -n shared-block-volume.vhd --size-gb 1024 --max-shares 3 -l westcentralus
   
   {
     "creationData": {
       "createOption": "Empty",
       "galleryImageReference": null,
       "imageReference": null,
       "sourceResourceId": null,
       "sourceUniqueId": null,
       "sourceUri": null,
       "storageAccountId": null,
       "uploadSizeBytes": null
     },
     "diskAccessId": null,
     "diskIopsReadOnly": null,
     "diskIopsReadWrite": 5000,
     "diskMbpsReadOnly": null,
     "diskMbpsReadWrite": 200,
     "diskSizeBytes": 1099511627776,
     "diskSizeGb": 1024,
     "diskState": "Unattached",
     "encryption": {
       "diskEncryptionSetId": null,
       "type": "EncryptionAtRestWithPlatformKey"
     },
     "encryptionSettingsCollection": null,
     "hyperVgeneration": "V1",
     "id": "/subscriptions/12345678910-12345678910/resourceGroups/sharedblock-rg/providers/Microsoft.Compute/disks/shared-block-volume.vhd",
     "location": "westcentralus",
     "managedBy": null,
     "managedByExtended": null,
     "maxShares": 3,
     "name": "shared-block-volume.vhd",
     "networkAccessPolicy": "AllowAll",
     "osType": null,
     "provisioningState": "Succeeded",
     "resourceGroup": "sharedblock-rg",
     "shareInfo": null,
     "sku": {
       "name": "Premium_LRS",
       "tier": "Premium"
     },
     "tags": {},
     "timeCreated": "2020-08-27T15:36:56.263382+00:00",
     "type": "Microsoft.Compute/disks",
     "uniqueId": "cd8b0a25-6fbe-4779-9312-8d9cbb89b6f2",
     "zones": null
   }

2. Verify that you have created the shared block volume by using the Azure command az disk show.

   $ az disk show -g <resource_group> -n <shared_block_volume_name>

   For example, the following command shows details for the shared block volume shared-block-volume.vhd within the resource group sharedblock-rg.

   $ az disk show -g sharedblock-rg -n shared-block-volume.vhd
   
   {
     "creationData": {
       "createOption": "Empty",
       "galleryImageReference": null,
       "imageReference": null,
       "sourceResourceId": null,
       "sourceUniqueId": null,
       "sourceUri": null,
       "storageAccountId": null,
       "uploadSizeBytes": null
     },
     "diskAccessId": null,
     "diskIopsReadOnly": null,
     "diskIopsReadWrite": 5000,
     "diskMbpsReadOnly": null,
     "diskMbpsReadWrite": 200,
     "diskSizeBytes": 1099511627776,
     "diskSizeGb": 1024,
     "diskState": "Unattached",
     "encryption": {
       "diskEncryptionSetId": null,
       "type": "EncryptionAtRestWithPlatformKey"
     },
     "encryptionSettingsCollection": null,
     "hyperVgeneration": "V1",
     "id": "/subscriptions/12345678910-12345678910/resourceGroups/sharedblock-rg/providers/Microsoft.Compute/disks/shared-block-volume.vhd",
     "location": "westcentralus",
     "managedBy": null,
     "managedByExtended": null,
     "maxShares": 3,
     "name": "shared-block-volume.vhd",
     "networkAccessPolicy": "AllowAll",
     "osType": null,
     "provisioningState": "Succeeded",
     "resourceGroup": "sharedblock-rg",
     "shareInfo": null,
     "sku": {
       "name": "Premium_LRS",
       "tier": "Premium"
     },
     "tags": {},
     "timeCreated": "2020-08-27T15:36:56.263382+00:00",
     "type": "Microsoft.Compute/disks",
     "uniqueId": "cd8b0a25-6fbe-4779-9312-8d9cbb89b6f2",
     "zones": null
   }

3. Create three network interfaces by using the Azure command az network nic create. Run the following command three times by using a different <nic_name> for each.

   $ az network nic create \
       -g <resource_group> -n <nic_name> --subnet <subnet_name> \
       --vnet-name <virtual_network> --location <location> \
       --network-security-group <network_security_group> --private-ip-address-version IPv4

   For example, the following command creates a network interface with the name shareblock-nodea-vm-nic-protected.

   $ az network nic create \
       -g sharedblock-rg -n sharedblock-nodea-vm-nic-protected --subnet sharedblock-subnet-protected \
       --vnet-name sharedblock-vn --location westcentralus \
       --network-security-group sharedblock-nsg --private-ip-address-version IPv4

4. Create three VMs and attach the shared block volume by using the Azure command az vm create. Option values are the same for each VM except that each VM has its own <vm_name>, <new_vm_disk_name>, and <nic_name>.

   $ az vm create \
       -n <vm_name> -g <resource_group> --attach-data-disks <shared_block_volume_name> \
       --data-disk-caching None --os-disk-caching ReadWrite --os-disk-name <new-vm-disk-name> \
       --os-disk-size-gb <disk_size> --location <location> --size <virtual_machine_size> \
       --image <image_name> --admin-username <vm_username> --authentication-type ssh \
       --ssh-key-values <ssh_key> --nics <nic_name> --availability-set <availability_set> --ppg <proximity_placement_group>

   For example, the following command creates a VM named sharedblock-nodea-vm.

   $ az vm create \
   -n sharedblock-nodea-vm -g sharedblock-rg --attach-data-disks shared-block-volume.vhd \
   --data-disk-caching None --os-disk-caching ReadWrite --os-disk-name sharedblock-nodea-vm.vhd \
   --os-disk-size-gb 64 --location westcentralus --size Standard_D2s_v3 \
   --image /subscriptions/12345678910-12345678910/resourceGroups/sample-azureimagesgroupwestcentralus/providers/Microsoft.Compute/images/sample-azure-rhel-8.3.0-20200713.n.0.x86_64 --admin-username sharedblock-user --authentication-type ssh \
   --ssh-key-values @sharedblock-key.pub --nics sharedblock-nodea-vm-nic-protected --availability-set sharedblock-as --ppg sharedblock-ppg
   
   {
     "fqdns": "",
     "id": "/subscriptions/12345678910-12345678910/resourceGroups/sharedblock-rg/providers/Microsoft.Compute/virtualMachines/sharedblock-nodea-vm",
     "location": "westcentralus",
     "macAddress": "00-22-48-5D-EE-FB",
     "powerState": "VM running",
     "privateIpAddress": "198.51.100.3",
     "publicIpAddress": "",
     "resourceGroup": "sharedblock-rg",
     "zones": ""
   }

Verification

1. For each VM in your cluster, verify that the block device is available by using the ssh command with your VM’s IP address.

   # ssh <ip_address> "hostname ; lsblk -d | grep ' 1T '"

   For example, the following command lists details including the host name and block device for the VM IP 198.51.100.3.

   # ssh 198.51.100.3 "hostname ; lsblk -d | grep ' 1T '"
   
   nodea
   sdb    8:16   0    1T  0 disk

2. Use the ssh command to verify that each VM in your cluster uses the same shared disk.

   # ssh <ip_address> "hostname ; lsblk -d | grep ' 1T ' | awk '{print \$1}' | xargs -i udevadm info --query=all --name=/dev/{} | grep '^E: ID_SERIAL='"

   For example, the following command lists details including the host name and shared disk volume ID for the instance IP address 198.51.100.3.

   # ssh 198.51.100.3 "hostname ; lsblk -d | grep ' 1T ' | awk '{print \$1}' | xargs -i udevadm info --query=all --name=/dev/{} | grep '^E: ID_SERIAL='"
   
   nodea
   E: ID_SERIAL=3600224808dd8eb102f6ffc5822c41d89