Last week, Microsoft announced the availability of preview bits for Azure Stack, an offering which allows customers to run Azure Services such as storage, PaaS Services and DBaaS within their own data centers or hosted facilities.

How is Azure Stack different from its predecessors like the Windows Azure Platform Appliance (WAPA) and Azure Pack (WAP), and why does Microsoft think it has a better chance of success? The answers to these questions hold special significance given that the narrative on private cloud has turned decidedly negative in the last 2-3 years.

Past attempts at Azure-in-a-box

To get a better understanding of Azure Pack’s unique features, let’s first take a quick background look at its predecessors, WAPA and Azure Pack.

WAPA was marketed as a combination of hardware (~1000 servers) and software (Azure services). The idea was that customers could drop this appliance within their own datacenter and benefit from greater geographical proximity to their existing infrastructure, physical control, regulatory compliance and data sovereignty. However, the timing of the release was less than ideal – WAPA was announced in 2012 during Azure’s early days when there was no real IaaS story. Additionally, the lack of a standard control plane across the various Azure services and the pace of change made operating the appliance unviable. The size (and cost) of this appliance meant that it initially appealed to a very narrow segment of customers, as only industry giants (eBay, Dell, HP) could reasonably afford to implement it.

WAP took a slightly different approach. Rather than trying to run Azure bits on-premises, it used a UI experience similar to that of Azure Portal (classic) to manage on-premises resources. Internally, the Azure Pack Portal depended on System Center 2012 R2 VMM and SPF for servicing requests. However, the notion of first-class software-defined storage or software-defined networking did not yet exist. Finally, WAP only made available one PaaS offering, the Azure Pack WebSites – a technology that made it possible to host high-density, web sites on-premises. The fact that other Azure PaaS offerings were not part of WAP was also a bit limiting.

How is Azure Stack different?

Azure Stack’s primary difference lies in the approach it takes toward bridging the gap between on-premises and the cloud. Azure Stack takes a snapshot of the Azure codebase and makes it available within on-premises data centers (Jeffery Snover expects biannual releases of Azure Stack). Given that Azure Stack is the very same code, customers can expect feature parity and management consistency. For example, users can continue to rely on ARM whether they are managing Azure or Azure Stack resources (in fact, Azure Stack quick start templates are now available as well in addition to the Azure quick start templates).

The following logical diagram depicts how the control plane (ARM) and constructs such as vNets, VM Extensions and storage accounts (depicted below the ARM) remain consistent across Azure and Azure Stack. This consistency comes from the notion of Resource Providers. The Resource Providers in turn are based on Azure-inspired technologies that are now built into Windows Server 2016, such as S2D (Storage Spaces Direct) and Network Controller.


What about Windows Service Bus? Windows Service Bus is a set of installable components that provide Azure Service Bus like capability on Windows servers and workstations. So in some sense it is similar to the Azure Stack concept. However, it should be noted that Windows Service Bus is based on same foundation as the Azure Service Bus (not a snapshot of Azure Service Code) and does not come with full UI and control plain experience that Azure offers.

Azure Stack Architecture

The following diagram depicts the Azure Stack logical components installed across a collection of VMs.

ADVM hosts services like AD, DNS, DHCP.

ACSVM hosts Azure Consistent Storage Services (Blob, Table and Administration services).

NCSVM hosts the network controller component that is a key part of software-defined-networking.

xRPM hosts the core resource providers, including networking storage and compute. These providers leverage Azure Service Fabric technology for resilience and scale-out.

This article provides a more detailed look at these building blocks.


The hybrid cloud is closer to the “plateau of productivity”

While the narrative on private clouds has turned decidedly negative, the demand for hybrid cloud continues to grow. This rise in demand is mainly due to the fact that public cloud adoption is set to spike in 2016 (just look at the strong growth numbers for public cloud providers across the board). This spike in usage is squarely based on enterprise IT’s growing interest in the public cloud. And as enterprise IT begins to adopt the public cloud, hybrid cloud is going to be at the center of this adoption. Why? Because despite all the virtues of the public cloud, legacy systems are going to be around for the foreseeable future – and this is not just due to security and compliance concerns: the enormity and pitfalls of legacy migration are well known.

So after languishing in the hype curve for years, hybrid IT may be finally reaching the proverbial Gartner plateau of productivity.

Azure Stack “hybrid” scenarios

Here are some example “hybrid” scenarios enabled by Azure Stack:

1) Dev/ Test in public cloud and Prod On-Premises – This model would enable developers to move quickly through proving out new patterns and applications, but would still allow them to deploy the production bits in a controlled on-premises setting.

2) Dev / Test in Azure Stack and Prod in Azure – This is the converse of scenario #1 above. The motivation for this scenario is that team development in the cloud is still evolving. Some challenges include: managing the costs of dev workstations in the cloud, collaborating across subscriptions (MSDN), and mapping all aspects of on-premises CI/CD infrastructure with services like VSO. This is why it may make sense for some organizations to continue to development on Azure Stack on-premises and deploy the production bits to Azure. Of course, as with scenario #1 above, this second scenario will require dealing with the lag in features and services between Azure and Azure Stack.

3) Manage on-premises resources more efficiently – Having access to modern portal experience (Azure Portal), automation plain (ARM), access cloud native services (Azure Consistent Services), as a layer over the existing on-premises infrastructure brings enterprises closer to the vision of FAST IT.

4) Seamlessly handle burst-out scenarios – Technologies like stretching on-premises database to Azure are beginning to appear. Azure Stack and its support for DBaaS make these hybrid setups even more seamless.

5) Comply with data sovereignty requirements – A regional subsidiary of a multi-national corporation may not have access to a local Azure DC. In such a situation, Azure Stack can help meet the data sovereignty requirements and at the same maintain overall consistency.

Promising offering. But don’t expect a silver bullet solution.

Azure Stack is fundamentally a different approach to hybrid IT. The fact that it is a snapshot of the Azure codebase will ensure consistency between on-premises and cloud. A common control plane and API surface is an additional plus.

However, the lag in features between the two environments will need to be carefully considered (as is the case today with differences in availability of services across various regions)

Even though customers are getting the same codebase, what they are *not* getting is seamless scalability and all the operational knowhow to run a complex underlying infrastructure. There is no getting around the deliberate capacity planning and operational excellence needed to efficiently run Azure Stack in your data center.

Finally, as organizations are increasingly realizing, adopting any form of cloud (public, private or hybrid) requires a cultural and mindset shift. No technology alone is going to make that transition successful.

With its unique approach to hybrid cloud, Azure Stack certainly looks to be a promising offering which will provide developers and IT Pros alike, an Azure consistent environment on-premises something was previously unavailable.