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Infratac Consulting: Hybrid Cloud Infrastructure Design | Patterns & Practices

Hybrid cloud is an integrated cloud service utilizing both private and public clouds to perform distinct functions within the same organization.

Organizations seeking to move applications into the cloud have five options: rehost on infrastructure as a service (IaaS), refactor for platform as a service (PaaS), revise for IaaS or PaaS, rebuild on PaaS, or replace with software as a service (SaaS), according to Gartner, Inc.

Cloud architects' design decisions must consider an organization’s requirements, evaluation criteria, and architecture principles; however, no alternative offers a silver bullet; all require architects to understand application migration from multiple perspectives and criteria, such as IT staff skills, the value of existing investments, and application architecture.

The alternative migration strategies many IT organizations consider are:

Rehost, i.e. redeploy applications to a different hardware environment and change the application’s infrastructure configuration. Rehosting an application without making changes to its architecture can provide a fast cloud migration solution. However, the primary advantage of IaaS, that - teams can migrate systems quickly, without modifying their architecture – can be its primary disadvantage as benefits from the cloud characteristics of the infrastructure, such as scalability, will be missed.

Refactor, i.e. run applications on a cloud provider’s infrastructure. The primary advantage is blending familiarity with innovation as “backward-compatible” PaaS means developers can reuse languages, frameworks, and containers they have invested in, thus leveraging code the organization considers strategic. Disadvantages include missing capabilities, transitive risk, and framework lock-in. At this early stage in the PaaS market, some of the capabilities developers depend on with existing platforms can be missing from PaaS offerings.

Revise, i.e. modify or extend the existing code base to support legacy modernization requirements, then use rehost or refactor options to deploy to cloud. This option allows organizations to optimize the application to leverage the cloud characteristics of providers' infrastructure. The downside is that kicking off a (possibly major) development project will require upfront expenses to mobilize a development team. Depending on the scale of the revision, revise is the option likely to take most time to deliver its capabilities.

Rebuild, i.e. Rebuild the solution on PaaS, discard code for an existing application and re-architect the application. Although rebuilding requires losing the familiarity of existing code and frameworks, the advantage of rebuilding an application is access to innovative features in the provider's platform. They improve developer productivity, such as tools that allow application templates and data models to be customized, metadata-driven engines, and communities that supply pre-built components. However, lock-in is the primary disadvantage so if the provider makes a pricing or technical change that the consumer cannot accept, breaches service level agreements (SLAs), or fails, the consumer is forced to switch, potentially abandoning some or all of its application assets.

Replace, i.e. discard an existing application (or set of applications) and use commercial software delivered as a service. This option avoids investment in mobilizing a development team when requirements for a business function change quickly. Disadvantages can include inconsistent data semantics, data access issues, and vendor lock-in.

Choosing the optimal application-migration option is a decision that cannot be made in isolation, Any cloud-migration decision is, in essence, an application or infrastructure modernization decision and needs to be approached in the broader context of related application portfolio management and infrastructure portfolio management programs.

This decision is not solely an issue of migration but is truly one of optimization: Which cloud platform and migration techniques offer the chance to optimize the application's contribution to stated and implied business and IT goals? Those business and supporting IT goals, should be driving any cloud migration decision — not a rush to experiment with new toys.

1.0               Private | Hybrid | Cloud Computing Adoption

Ask IT industry analysts about enterprise cloud adoption, and they’ll tell you it’s all about hybrid. Sure, startups might build entirely on the public cloud, but no large enterprise is going to move everything wholesale to AWS, Azure, or Google Cloud.

Instead, they’ll build some sort of private cloud, create new stuff on (and/or migrate some old stuff to) the public cloud, and closely integrate the two -- the definition of the hybrid cloud.

The question is, if you need a private cloud to have a hybrid cloud, where are all the private clouds?  Not talking about merely well-managed virtualization. At a bare minimum, self-service capabilities so that developers can provision their own VMs (and these days, run containers on top of them). At the high end, I'm envisioning production implementations that operate at large scale.

For self-service to work, you need automation -- or basically a library of scripts that perform common tasks: server provisioning, shared storage setup, network settings for a VLAN, and so on. Better yet, you should have orchestration to assemble those automated tasks into predefined workflows for specific applications or services.

Who are Key Players in the Private Cloud Space

Microsoft—A considerable chunk of private cloud functionality is already in place with Microsoft’s Azure Pack, including IaaS-like virtualization management, self-service portal functionality, SQL Server (or MySQL) as a service, service management APIs, and so on.

Eucalyptus—simply put, is a private cloud version of Amazon Web Services (AWS). The idea of a private cloud version of AWS is a good one. Many enterprises want to migrate to private and hybrid cloud computing first, then shift exclusively to public at some point in the future.

VMware—today still has the biggest share of the private cloud market, depending on how you define it.  VMware still dominates virtualization. But it’s difficult to tell to what degree customers have implemented VMware’s vRealize Suite, which includes the whole complement of monitoring, self-service, log analysis, and automation capabilities.  

What does "hybrid" from a practical perspective really mean anyway?

Workloads run where they want to run. Some need cloud scalability and automation and self-service. Others, including legacy client-server workloads, crank along fine the way they are. Some require so much scale that you don’t want to pay a third party to host it because the operational and business dependency costs are too steep.

The overall vision of parallel private and public clouds, is where you can shift workloads around at will, workloads have a tendency to stay where you first deployed them. Containers may make that more fluid, but that portability does not necessarily demand a parallel hybrid scenario.

The bottom line is that in a modern enterprise, systems must always be integrated, whether they’re local or remote. But the hybrid idea of a private cloud as a continuous fabric extending into the public cloud is going to remain a remote possibility for most customers, mainly because the trouble and expense of building the private portion at scale remains so formidable.

Therefore, when talking to your cloud computing advisor—Infract Consultant; understand that s/he will focus not only on technology, but also on identifying and determining  an optimal approach and understanding of not only the raw cloud enabling technology infrastructure components, but also and more importantly, the business context and desired outcomes from recommended patterns and best practices for implementation.

Related resources

Amazon Web Services   Amazon

Azure Trust Center         Microsoft

The Hybrid Cloud Model provides the best of both private and public worlds. It combines the economies and efficiencies of public cloud computing with the security and control of private cloud. However, marrying public and private cloud services requires advanced thinking and some handy technology.

Emerging Approaches to Hybrid Cloud Computing

Static Placement

Architectures in which the location of applications, services and data is tightly bound to private or public clouds.

Assisted Replication

Architectures in which some applications, services and data can be replicated from private to public clouds – or vice versa.

Auto Migration

The code or entire virtual machines (VMs) that move between private and public cloud instances, usually through human intervention, but sometimes through an automated process.

Dynamic migration

Moving VM instances between private and public clouds, as if both the public clouds and private clouds existed in the same virtual OS

Five Options for Migrating Applications to the Cloud: Rehost, Refactor, Revise, Rebuild or Replace