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Most organizations aren't willing to cede all IT operations to the public cloud. Instead, they want the flexibility to run workloads on both shared infrastructure as a service and private infrastructure. The problem, however, is that private virtual machine infrastructure and the public cloud are based on different technology stacks. Microsoft intends to bridge that gap and address other hybrid cloud challenges with Azure Stack.
Azure Stack is a private instantiation of core Azure services that share code, APIs and a management portal with the Azure public cloud. Microsoft unveiled the first public preview of Azure Stack in January, noting that customers demanded a more consistent cloud platform that can span hybrid environments.
Hybrid cloud challenges remain
Hybrid cloud adoption is growing among cloud users. However, key barriers remain to a successful hybrid implementation, including a lack of cloud expertise, the complexities of building a private cloud and the difficulty of managing multiple cloud services.
Each of these hybrid cloud challenges is exacerbated by the fact that, so far, the typical hybrid implementation uses different stacks for public and private infrastructure, such as Amazon Web Services (AWS) with VMware vSphere or vCloud. The ability to share a common cloud stack across public and private instances could mitigate some hybrid cloud challenges -- which is Microsoft's vision for Azure Stack.
Azure Stack a work in progress
Azure Stack delivers public-private integration at multiple levels: infrastructure as a service (IaaS), platform as a service (PaaS) and service delivery. It provides baseline infrastructure services, such as compute, object and block storage and virtual networking, as well as application platform services, like databases, message queues and Azure Web Apps. Cloud admins perform service management and delivery through a common portal, the Azure Resource Manager, where private Azure Stack instances appear as another deployment region alongside Azure public cloud locations.
Azure Stack is currently in technical preview, with an official release expected later this year. Even then, Azure Stack won't provide the full gamut of Azure features, but will offer the most fundamental ones, including:
- Compute: Virtual machines (VM), including extensions, availability sets and desired state configuration, as well as containers;
- Storage: Blob storage and tables;
- Networking: Virtual network, load balancer and virtual private network (VPN) gateway;
- Database: SQL and MySQL;
- Integration: Storage queues, or asynchronous message queues;
- PaaS: Azure Web Apps;
- Management: Azure Resource Manager portal, Key Vault, VM image gallery and depot; and
- Development: Azure software development kit, PowerShell and command-line interfaces, as well as native Visual Studio support.
Upon general availability, Azure Stack is also expected to include:
- Service Fabric: Serverless and auto scaling microservices, similar to AWS Lambda;
- Premium Storage: High-performance, solid-state drive (SSD)-based storage for high IOPS and VM workloads, such as database applications; and
- Additional PaaS: Azure Mobile Apps and Logic Apps services, as well as the API Apps service.
Notably missing from Azure Stack are services for data analytics and Internet of Things, such as Azure Machine Learning, HDInsight Data Factory and Stream Analytics, as well as some data services like Azure Data Warehouse, Search and Redis Cache. Azure Stack also lacks media and content delivery and integration services, such as BizTalk and Service Bus. Microsoft has said it will evaluate customer demand for these missing features to prioritize future enhancements. Organizations can also extend Azure Stack with third-party resource providers.
Private cloud, but not DIY
Although Azure Stack is designed to run on infrastructure that enterprise IT teams own and operate, Microsoft doesn't anticipate most organizations will do the necessary hardware deployment and integration. Azure Stack will only be supported on vetted hardware, and Microsoft will publish a hardware compatibility list prior to release. However, since the resource requirements will be significant and stringent, Microsoft expects most users to buy new hardware purpose-built for Azure Stack.
One useful prototype is Dell's Microsoft Cloud Platform System, but other converged infrastructure providers, such as Hewlett Packard Enterprise and Lenovo, will likely offer rack-level products that integrate servers, storage and networking designed for Azure Stack.
Azure Stack deployments will require at least four physical servers and scale up to 63-node clusters, however the preview release can run on a single machine. The minimum and recommended configuration is:
- Dual Xeon CPU with 12 to 16 cores
- Ninety-six to 128 GB of RAM
- One OS disk with 200 GB available -- SSD or hard disk drive
- Four data disks with 140 to 250 GB per disk -- SSD or hard disk drive
Since Azure Stack provides some of the same services, through the same management portal, as the Azure public cloud, everything IT teams do on the private Azure Stack instance can be migrated to Azure public IaaS. This makes Azure Stack ideal for testing and developing new applications and services. Current Azure users can download the preview release to start kicking the tires.
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