TOP 5 Benefits of Azure Dedicated Hosts for SQL Server Workloads on Azure VMs
Published Aug 22 2019 10:01 AM 8,136 Views

SQL Server on Azure virtual machines (SQL VM) enables migrating SQL Server workloads to the cloud at the lowest TCO [1]. You have the flexibility to choose version and edition of SQL Server and the operating system, VM type and size, and HADR deployment architecture. SQL VM’s can be licensed with Azure Hybrid Benefit with existing SQL Server licenses or with PAYG (Pay As You Go) model where SQL Server license is paid based on usage.


Registering with SQL VM RP creates an Azure SQL VM resource integrated into the unified Azure SQL platform and enables comprehensive manageability feature set to reduce heavy SQL Server administration cost. Management services to automate backup, automate Always On AG, automate patching, threat detection and vulnerability assessment are available to opt-in once registered.

Microsoft Azure allows you to run applications and virtual machines, including SQL VM’s, on shared physical infrastructure to offer the lowest infrastructure costs while working continuously to ensure multi-tenant architecture of Azure supports security, confidentiality, privacy, integrity, and availability standards.


Recently introduced, Azure Dedicated Host Preview provides single-tenant physical servers that can host one or more virtual machines. With this new hosting model, physical server is dedicated to your organization and capacity isn’t shared with other customers. Physical server-level isolation helps to address security and compliance requirements, brings visibility and control over the server infrastructure and enables significant cost savings and licensing flexibility for SQL Server workloads on Azure VMs.


We will discuss top benefits of Azure Dedicated Hosts for SQL Server workloads below.


Physical Isolation

Multi-tenancy improves efficiency by multiplexing resources among customers but also introduces the risk of sharing physical servers and other infrastructure resources when running your sensitive applications and VMs that may belong to an arbitrary user. Azure Compute offers virtual machine sizes that are Isolated to a specific hardware type and dedicated to a single customer. Utilizing an isolated size guarantees that your virtual machine will be the only one running on that specific server instance. The current isolated virtual machine offerings commonly used to host SQL Server workloads include E64is_v3, M128ms and DS15_v2, learn more about isolated sizes available here.


With dedicated hosts, you can isolate all your organization’s SQL VMs at the physical server level. You can run any number of Azure VMs part of the same VM-Series within the core and memory capacity limits of a dedicated host. For example, on a dedicated host type 1 DSv3 VM series, you can deploy ‘4-D2s v3 VMs + 4-D4s v3 VMs + 5-D8s v3 VMs’ or ‘2-D16s v3 VMs + 1-D32s v3 VMs’ all on a physical server dedicated to your organization.



Azure Dedicated Hosts provide visibility over the server infrastructure running your SQL VMs. On dedicated hosts, you gain control over the underlying hardware infrastructure by selecting the host type, Processor brand, and size of the Azure Virtual Machines you want to deploy.


Hosting SQL VMs on an isolated and dedicated physical server with extended monitoring, visibility and control at the host level can help addressing compliance requirements about physical security, data integrity, and monitoring.


Control Failovers

Microsoft Azure periodically updates its platform to improve the reliability, performance, and security of the host infrastructure for virtual machines. These updates range from patching software components in the hosting environment to upgrading networking components or decommissioning hardware. Dedicated hosts offer maintenance control with an option to skip regular platform updates, then apply it at the time of their choice within a 35-day window.


High availability configurations for Azure VM’s do not assure SQL Server’s availability. You need to configure SQL Server high availability and disaster recovery technologies like Always On Availability Groups, Always On Failover Cluster Instances, Log Shipping or SQL Server Backup and Restore with Azure Blob Storage Service to assure SQL Server’s high availability on Azure VMs. With the maintenance control feature of dedicated hosts, you can reduce and control SQL Server failovers by moving all host updates to your maintenance window and reduce host restarts.


Significant Cost Savings with Unlimited Virtualization

Azure Dedicated hosts bring significant cost savings opportunity for SQL Server workloads with additional Azure Hybrid Benefit rights on dedicated environments. SQL Server Enterprise Edition licenses with Software Assurance enables “unlimited virtualization” rights for SQL Server workloads on Azure Dedicated Hosts. With unlimited virtualization rights, you can license only the physical cores of the dedicated host and be eligible to use all virtual cores. Azure dedicated hosts use 2:1 virtualization ratio and enables up to 50% SQL Server license cost savings.


For example, to license Dedicated Host Type 1(DSv3 series or Esv3 series) with SQL Server AHB, 32 cores of Enterprise Edition SQL Server licenses are required (as 32 physical cores are available to use by workloads, 8 physical cores are used for virtualization on type-1 hosts). With only 32 cores of Enterprise Edition SQL Server licenses, you get access to all 64 virtual cores of the host. If you deploy an E64 vs3 or D64s v3 VM on a multi-tenant host, you should have 64 cores of SQL Server licenses with SA. But, by licensing a type 1 dedicated host with SQL Server AHB, you can host E64 v3 or D64s v3 VM’s at half SQL Server license cost.


Azure dedicated hosts offers existing hardware on Azure data centers; because of that, performance of the VM’s on dedicated hosts versus multi-tenant hosts do not change. You can access to the same resources up to half of the SQL Server license cost if you choose to license the dedicated host with SQL Server AHB.


Licensing Flexibility

You can choose either licensing the dedicated host or licensing VM’s on the dedicated host for SQL Server.


License the dedicated host for SQL Server

Dedicated hosts can be licensed for SQL Server with SQL Server AHB model or with SQL Server Licenses acquired before October 1st, 2019. Licensing the host with SQL Server AHB is recommended as it is the most cost efficient model with savings up to 50%.


An alternative licensing option is available by using SQL Server Enterprise Edition licenses acquired before October 1st, 2019. This model does not require software assurance, but does not enable “unlimited virtualization” benefit. If we go through the same example, to license a type-1 dedicated host (DSv3 series or Esv3 series) for SQL Server with the SQL Server Enterprise Edition licenses acquired before October 1st, 2019; you should have 40 cores of SQL Server Enterprise Edition.


Dedicated Host level licensing will always override VM level licensing model; all SQL Server license charges will be removed from the VM’s and SQL Server license tracking will be managed at the dedicated host level if host is licensed for SQL Server.


License Virtual Machines for SQL Server

If you plan to use the dedicated host for multiple workloads including SQL Server, then you might choose to license SQL server on the VM level not on the dedicated host level. If the dedicated host is not licensed for SQL Server, then VM level licensing rules will apply. You can continue with AHB or PAYG licensing for SQL Server at VM level the same as with multi-tenant VMs.


Create VMs on a dedicated host (preview) to isolate your organization’s workloads, save licensing costs, assure organizational compliance and control SQL server failovers today. If you have a question or would like to suggest, you can contact us through User Voice. We look forward to hearing from you!



[1] Total cost of ownership (TCO) is up to five times lower than with SQL Server on Amazon Web Services EC2. Cost difference includes Azure Hybrid Benefit for Windows Server (exclusive to Azure) and a three-year offer of free Extended Security Updates in Azure Virtual Machines for no additional costs. Prices are as of October 24, 2018 and subject to change. Actual regional pricing and program discounts may apply. Actual savings may vary based on region, instance size, and performance tier. Savings exclude Software Assurance costs, which may vary based on Volume Licensing agreement. Contact your sales representative for more information. Learn more.


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‎Feb 27 2020 11:44 AM
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