Are you ready for Multi-Cloud?


Guest Post by Tommy Tang – Cloud Evangelist 

Lately I have heard colleagues earnestly discussing (or perhaps debating) the prospect of adopting Multi-Cloud strategy; and how it could effectively mitigate risks and protect the business as it was a prized trophy everyone should be striving for. For those uninitiated Multi-Cloud strategy in a nutshell is a set of architecture principles that would facilitate and promote the absolute freedom to select any cloud vendor for any desired service at time of your choosing; and there is no material impact to move from one cloud service provider to another.

Before you get too excited about Multi-Cloud I’d like to mention the much publicised US Department of Defence’s Joint Enterprise Defence Infrastructure cloud contract (aka JEDI). Amongst the usual objectives and strategies stated in the JEDI strategy document, the most contentious issue revolves around the explicit requirement for choosing a single cloud service provider who can help modernise and transform their IT systems for the next 10 years. Not Multi-Cloud. The reaction to the single cloud approach has certainly brought on some fierce debate in the IT world, of which both IBM and Oracle tried to register their displeasure through legal avenues. Both companies have been dismissed and out of the running of the JEDI contract now.

While you are pondering the reason why Department of Defence would seemingly go against the conventional wisdom of Multi-Cloud, let’s briefly examine some of the advantages and disadvantages of Multi-Cloud strategy.


  • Mitigate both service and commercial risks by procuring from multiple cloud vendors (i.e. not putting all eggs in one basket)
  • Select the best-in-bred service from a wide range of cloud providers (E.g. AWS for DevOps, Azure for Business Intelligence and Google for Artificial Intelligence)
  • Strive for favourable commercial outcome by encouraging competition between different players
  • Leverage fast emerging new technologies and services offered by the incumbents or new cloud entrants
  • Promote innovation and continuous improvement without artificial cloud boundaries


  • Multi-Cloud architecture design can be more complex (I.e. integration, replication and backup solution that would need to work across different cloud vendors)
  • Unable to take advantage of vendor specific feature or service (E.g. Lambda is an unique AWS service)
  • Difficult to track and consolidate finance with different contracts and rates
  • No single pane-of-glass view for monitoring and managing cloud services
  • Need extensive and continuous training for different and never-ending cloud technologies

After learning the good and bad of pursuing the Multi-Cloud dream do you think the JEDI approach is wrong? Well the answer in my humble opinion is it depends. For example if you’re managing an online holiday booking service then you’re probably already using cloud services and thus it’s unlikely you’d face any impediments for deploying your Java applications to a different cloud vendor. On the other hand if you’re running the traditional supermarket and warehouse business using predominately on-premises IT systems then it is much more difficult moving them to the cloud; let alone running in different cloud vendors without massive overhaul.

If you’re still keen to explore the Multi-Cloud strategy then I’d consider the following guidelines. These are not prerequisites but certainly help achieve the ultimate cloud-agnostic goal.

Modernise IT Infrastructure

Modernise the on-premises IT systems to align with the common cloud infrastructure so they are Cloud Ready, This is the most important step regardless whether you are aiming for single cloud or Multi-Cloud deployment. During the modernisation phase you’d soon find out certain IT systems are difficult (and insanely expensive) to move to the cloud. This is the reality check you ought to have. It is perfectly ok to retain some on-premises system because quite frankly not every system is suitable for cloud. For instance large and complex application that requires specialised hardware or highly latency sensitive application is probably not for the cloud. Quarantine your cloud disenchanted applications quickly while consolidating cloud friendly applications into Intel-based virtualised platform. (E.g. VMWare or Hyper-V) Modernised on-premises virtualised platform provides the cloud foundation with added benefits of running virtual infrastructure. It is a good strategy for either Multi-Cloud or hybrid cloud. You should take full advantage of the existing data centre while you are embarking on the 3-5 year cloud journey.

Modular Application Design

Application development cost typically outweighs the infrastructure cost by a factor of 3x-5x. Given AppDev is quite expensive it is absolutely paramount to get it right from the start. The key design objective is to create an application that is highly modularised, loosely-coupled and platform agnostic. Hence the application can run on different cloud services without incurring massive redevelopment cost. The latest trendy term that everyone has been using is Microservice. Microservice is not bound to a specific framework or programming language. Any mainstream language like Java, C# or Python is suitable depending on one’s own preference. Apart from the programming language I’d also like to touch on application integration. I understand many people would prefer developing their own APIs because it is highly customisable and flexible. However in today’s cloud era it’d require lots of effort and resources to develop and maintain APIs for different cloud vendors as well as on-premises IT systems. Unless there is a compelling reason I’d consider using specialised API vendor like MuleSoft to speed up and simplify development. Last but not least I’d also embrace Container technology for managing application deployment. (E.g. Kubernetes) Containerised application capsule can significantly enhance portability when moving between clouds.

Data Mobility

It is about your prerogative over your own data. When you are considering Multi-Cloud strategy one of the burning issues is how to maintain data mobility. Data that is stored in the cloud can be extracted and moved to on-premises IT systems or another cloud service providers as desired without restrictions. Any impediment to data mobility would seriously diminish the benefits of using cloud in the first place. In the new digital world data should be treated as capital with intrinsic monetary value and therefore it is unacceptable for data to be placed with restrictive movement. So how do you overcome data mobility challenges? Here are some basic principles you should consider. First one is data replication. For instance is it acceptable to the business if the application would take 5 days to move from AWS to Azure? How about 4 weeks? The technology that underpins the Multi-Cloud strategy must meet the business needs otherwise it becomes totally irrelevant. Data replication between different cloud platforms can be implemented to ensure data is always available in multiple destinations of your choice. Native database replication tool is a relatively straightforward solution for maintaining 2 independent data sources. (E.g. SQL Always-OnOracle Data Guard) The second principle is to leverage specialised cloud storage provider. Imagine you can deploy applications to many different cloud vendors while retaining data in a constant readily accessible location. The boundaries of Multi-Cloud would simply dissipated. For example NetApp Data ONTAP is one of the leading contestants in the cloud storage area. The third principle is the humble long standing offsite backup practice. Maintaining a secondary data backup at alternate site is an absolute requirement for both cloud or non-cloud system. It is a very cost effective way of retaining full data control and avoiding vendor lock-in.

Multi-Cloud is a prudent, agile and commercially sound strategy with many benefits but I believe it is not suitable for everyone. Blindly in pursuit of Multi-Cloud strategy without compelling reason is fraught with danger. The decision made by US Department of Defence to partner with only one cloud vendor, which is yet to be determined at the time of writing this article, is one of the high profile exception. Time will tell.

Check out this link where we dive deeper in to the difference of IAAS resilience on AWS and Azure.

This article is a guest post by Tommy Tang ( Tommy is a well rounded and knowledgeable Cloud Evangelist with over 25+ years IT experience covering many industries like Telco, Finance, Banking and Government agencies in Australia. He is currently focusing on the Cloud phenomena and ways to best advise customers on their often confused and thorny Cloud journey.