Top Ten things to consider when moving Business Critical Applications (BCA) to the Cloud (Part 2 of 3)

In the first part we looked at public, private and Hybrid Cloud and their characteristics. In this part we will look at the common characteristics of business critical applications. We will also look at how some of these characteristics relate to the different types of Cloud infrastructure.

Common Characteristics of Business Critical Applications (BCA):

Business critical applications typically have very stringent SLAs and have a direct impact on the business. These are the crown jewels of the business that need to be managed with utmost care to avoid loss of productivity, data and potential revenue. These are the major factors can have a direct impact on these applications such as the following:


Figure 6: BCA Cloud Considerations


A majority of BCA requires high performance, which is typically guaranteed to the business in the form of an SLA. Performance can have a direct impact on productivity and revenue for the business. Due to the inherent shared nature of public clouds, they are not able to provide performance guarantees for BCA.

High Availability:

High Availability has always been a critical requirement for BCA. Enterprises typically require four to five nines of availability for these applications. Public clouds today do not provide HA for customers. Customers are required to re-architect their applications for more resiliency and HA. Customers have spend extra effort to have high availability in Public cloud environments. Private and Hybrid Clouds have built in HA capabilities that BCA can leverage.


BCA needs an infrastructure that can scale up or down as and when needed. Public clouds are highly scalable providing elastic scaling capabilities. Virtualized private clouds leveraging technologies like Hot-Add can also dynamically scale up or scale down resources needed for BCA. Short term bursting and scalability can be best done leveraging public clouds.

Security & Compliance:

Business Critical Data often have very stringent security requirements. It is also common for this data to be subject to industry and government regulations for audit and compliance. The sensitivity and other export regulations of the data can also determine whether these have to be stored in house or by an external provider. The public cloud providers provide robust tools to manage the environment securely to meet common business requirements. The information security team of the enterprise has to adapt its people and processes to leverage the tools of the public cloud provider. Private clouds can leverage existing toolsets and can also meet regulatory requirements, with fine-grained control and storing the data where appropriate. There is a lot of effort and complexity required in compliance processes and the solution should provide a lot of features and flexibility. Public Cloud based solutions might undergo additional scrutiny with extra steps required for compliance.


Businesses leverage tools to manage and maintain their BCA. These tools are quite often evaluated, optimized and deployed over an extended period of time with the internal teams being trained to effectively use these tools. Public clouds provide tools as part of the service to customers that require customers to adapt and retool their processes around. Private clouds can continue to leverage existing tools and processes for management of BCA.


Due to the critical nature of BCA, cost takes a back seat to factors like Performance, Availability and other SLA related considerations. The potential loss in revenue, productivity, etc. counters the need for reduced cost. Private and Hybrid clouds are the best suited for BCA from a cost perspective. Public clouds can be cost prohibitive due to the need for BCA to operate 24X7X365 and the pay as you go metering of these applications.


Robust operations are very important for managing BCA. BCA infrastructure should be managed reliably to meet the SLAs required by the business. A combination of a people, process and technology make operations happen. Public clouds are operated upon by the operations team of the cloud provider. In addition, operational aspects from a customer standpoint need to be done by internal teams. The split in the operational tasks helps reduce costs, but there is less coordination and control of the environment. Private clouds are managed by the internal team, with full accountability for all operational aspects of the environment.


New BCA under consideration are typically prototyped with a proof of concept as part of a feasibility study and the decision making process. The need for infrastructure for prototyping is for a short duration with quick turnaround for infrastructure readiness. Public Cloud providers are very adept at providing needed infrastructure quickly and for short-term needs. Private cloud providers do not necessarily have spare infrastructure for such needs and the turnaround time is likely to be much longer for Prototyping needs.

Disaster Recovery:

Disaster Recovery is a broad area that includes backup of critical data and the ability to recover from minor and major disasters. BCA data need to be protected from disasters to comply with business and regulatory requirements. Legacy disaster recovery protections for BCA involved having a dedicated identical infrastructure in a secondary site used only during testing and actual disasters. Virtualization and Cloud computing has greatly simplified DR for BCA through automation tools and the ability to transfer entire virtual machines to the DR site, where they can be recovered on completely different hardware. The need for disaster recovery infrastructure is only short term and Public Cloud Pay as you go capabilities fit these requirements well.

Vendor Lock In:

This is a very important criterion for BCA. If a cloud vendor is very proprietary and makes it hard for customers to move out, the customer loses control over their infrastructure and its costs. Public cloud vendors traditionally lock in their customers. They provide robust tools to move in, but scant tools to move out. Lock in can be avoided by using Public Cloud providers intelligently for the requirements that are least impacted by it.

BCA Cloud Criteria Analysis:

Based on our discussions about requirements for business critical applications and how different cloud options stack up against each other. For the sake of this analysis, we will classify SAAS as also a Public cloud technology to make the comparison simpler. Neither the Public nor the Private cloud on their own meet all the requirements for BCA. One can combine the two methodologies appropriately and leverage hybrid cloud to get the best of both worlds and at the same time efficiently run BCA in the cloud.


Figure 7: BCA Criteria match by cloud type

Performance: Private Clouds can guarantee the performance for BCA, while Public Clouds cannot due to their shared nature.

High Availability: HA solutions are more prevalent and available in private clouds, while these have to be architected into public cloud solutions.

Scalability: Public cloud solutions have unbounded resources and is more scalable than resource constrained private clouds. One can mix and match these and potentially burst to public clouds for certain high demand short-term application needs.

Security: Even though Public clouds do provide robust security tools, the external location of the data and its management makes it not compatible with all security requirements. Private clouds can be customized to meet all security requirements.

Tools: Robust tools are available in both the private and public clouds for BCA management.

Cost: For short term needs the pay as you go public cloud model can be cost effective. For round the clock applications, the private cloud is cost effective. A hybrid cloud with a mix of these two cost models would provide the most effective solution.

Operations: The public cloud includes infrastructure operations as part of the service, but customer specific processes have to be managed by customer operations. In private cloud a single team manages both components. Private cloud management requires more personnel and could be more expensive. A Hybrid cloud can leverage the best of both worlds.

Prototyping: Prototyping and proof of concepts are best addressed in Public Clouds with fast turnaround for infrastructure with a Pay as you go model. Private clouds are not adequately suitable for these requirements.

Disaster Recovery: Public clouds are great for providing infrastructure on a needed basis. Rather than have dedicated infrastructure for disaster recovery, it can be leased for testing and disasters for the short duration of the events. Another consideration when it comes to disaster recovery is what kind of conversion if any is required to run the BCA workload with the cloud provider. The Recovery Time Objectives (RTO) for BCA are very stringent and any conversions across platforms will significantly increase the time to recover. Ideally if the BCA is recovered in a platform identical to the source and automatic tools are leveraged excellent RTO can be achieved. The time required for testing is also dependent on compatibility between the source and destination platforms.