PowerFlex and Azure Arc-enabled data services architectures deliver the Azure data services capability on flexible software-defined storage with linearly-scaling performance and network throughput. The SQL Managed Instance and PostgreSQL Hyperscale services for Microsoft Azure Arc are available with or without a direct Azure connection. Both these modes allow you to get the latest releases from Azure and receive regular updates on patches and new features.

The Azure Arc data controller is a collection of Kubernetes resources, that orchestrates the Azure Arc data services architecture. It provides maximum flexibility and consistency across platforms along with a range of management capabilities including provisioning, monitoring, elastic scaling, automated updates, high availability, and backup. 

Two types of connectivity modes are available for the data controller:

• Direct mode – Intended for organizations who maintain network connectivity to Azure and prefer to leverage Azure Resource Manager – including Azure portal and Azure CLI – for management of this DBaaS architecture. Usage data, metrics, and logs are automatically sent to Azure.
• Indirect mode – Intended for organizations with limited or no connectivity to Azure because of data sovereignty, data gravity, or other similar security requirements. DBAs use tools like Azure Data Studio and Azure CLI (az) with the arcdata extension to manage the data controller directly. This mode requires manual uploads of usage data, metrics, and logs to Azure using the Azure CLI. This is the connectivity mode that we used in this deployment example.

Indirect connectivity mode prerequisites

The prerequisites to deploy data controller in indirect mode are:

• Install or upgrade all the client tools to the latest available versions in accordance with the Azure Arc-enabled data services pre-requisites. 
• Connect the Kubernetes cluster to Azure using Azure Arc-enabled Kubernetes.
• Create the service principal and roles for metrics. Then assign the service principal to the appropriate role – Monitoring Metrics Publisher – for uploading usage data, metrics, and logs to Azure Monitor. 

Note: In this deployment example the service principal name (SPN) was scoped at the subscription level, because this was the only setup used. Microsoft documentation provides commands for more granular scope, such as at the resource group level.

The following Azure CLI commands are run to create the SPN.

az ad sp create-for-rbac --name azure-arc-metrics --role Contributor --scopes /subscriptions/<subscription ID>

az role assignment create --assignee <application ID> --role 'Monitoring Metrics Publisher' --scope subscriptions/<subscription ID>

The first command produced the following output. These values are used during the deployment of the data controller:

{

  "appId": "<application ID>",

  "displayName": "azure-arc-metrics",

  "name": "http://azure-arc-metrics",

  "password": "Xt3OLAd51U420fTOBd.K5C.0i0Ihxb7nNT",

  "tenant": "<Azure Active Directory tenant ID>"

}

For Azure arc data controller pre-requisites and deployment options, see Microsoft Azure Arc on Dell EMC PowerFlex | Dell Technologies Info Hub.

Deploy Azure Arc-enabled data services data controller in indirect connectivity mode

The data controller in indirect connectivity mode is deployed using Azure Data Studio or Azure CLI. For this deployment, we used the Azure CLI, as shown in the following code sample:

$ENV:AZDATA_USERNAME = $arcDataControllerAdminUsername

$ENV:AZDATA_PASSWORD = $arcDataControllerAdminPassword

$ENV:dcName = $arcDataControllerName

$ENV:SUB = $azSubId

$ENV:RG = $azResourceGroup

$ENV:AZDATA_LOGSUI_USERNAME=$arcDataControllerAdminUsername

$ENV:AZDATA_LOGSUI_PASSWORD=$arcDataControllerAdminPassword

$ENV:AZDATA_METRICSUI_USERNAME=$arcDataControllerAdminUsername

$ENV:AZDATA_METRICSUI_PASSWORD=$arcDataControllerAdminPassword

az arcdata dc create `

--connectivity-mode indirect `

--name $arcDataControllerName `

--k8s-namespace arc `

--subscription $azSubId `

--resource-group $azResourceGroup `

--location eastus `

--storage-class vxflexos-xfs `

--profile-name azure-arc-kubeadm `

--infrastructure onpremises `

--use-k8s

For more information, see the Reference link for the data controller deployment.

Deploy SQL Managed Instances

SQL Managed instances in indirect mode are deployed from the PowerShell using Azure CLI commands or from the Azure Studio after the data controller is connected. In this setup, the Azure CLI scripts were used to deploy the SQL Managed Instances. 

Ten General Purpose SQL Managed Instances and three business-critical instances are deployed to run the test cases mentioned in the following sections, ranging from 2vCPU/4 GiB memory to 16vCPU/ 16 GiB memory. These instances are deployed on the four Kubernetes worker nodes with PowerFlex volumes automatically created as the persistence layer. 

For the scripts to deploy a SQL MI, see the SQL MI creation Scale-up scenario section of this document.

Backup and Restore options for a SQL Managed Instance

Azure Arc-enabled data services SQL MIs have an integrated automatic backup feature enabled. This feature triggers a full database backup, a differential backup, and a log backup when a new database is created or restored from other databases. These backups are stored in a backup storage class that is specified during the SQL MI deployment. The backups are retained in accordance with the –retention-days value. This value can be set between zero and 35 days. The default value is seven.

The SQL database backup and restore operations are monitored and performed from Azure Studio.

For more information about SQL MI point-in-time capabilities and features, see point-in-time restore.