Kloud receives a lot of communications in relation to the work we do and the content we publish on our blog. My colleague Hugh Badini recently published a blog about Azure deployment models from which we received the following legitimate follow up question…

So, Murali, thanks for letting us know you’d like to know more about this… consider this blog a starting point :).

Firstly though…

this topic (inter-cloud migrations), as you might guess, isn’t easily captured in a single blog post, nor, realistically in a series, so what I’m going to do here is provide some basics to consider. I may not answer your specific scenario but hopefully provide some guidance on approach.

Every cloud has a silver lining

The good news is that if you’re already operating in a cloud environment then you have likely had to deal with many of the fundamental differences between traditional application hosting and architecture and that of cloud platforms.

You will have dealt with how you ensure availability of your application(s) across outages; dealing with spikes in traffic via use of elastic compute resources; and will have come to recognise that is many ways, Infrastructure-as-a-Service (IaaS) in the cloud has many similarities to the way you’ve always done things on-prem (such as backups).

Clearly you have less of a challenge in approaching a move to another cloud provider.

Where to start

When we talk about moving from AWS to Azure we need to consider a range of things – let’s take a look at some key ones.

Understand what’s the same and what’s different

Both platforms have very similar offerings, and Microsoft provides many great resources to help those utilising AWS to build an understanding of which services in AWS map to which services in Azure. As you can see the majority of AWS’ services have an equivalent in Azure.

Microsoft’s Channel 9 is also a good place to start to learn about the similarities, with there being no better place than the Microsoft Azure for Amazon AWS Professional video series.

So, at a platform level, we are pretty well covered, but…

the one item to be wary of in planning any move of an existing application is how it has been developed. If we are moving components from, say, an EC2 VM environment to an Azure VM environment then we will probably have less work to do as we can build our Azure VM as we like (yes, as we know, even Linux!) and install whatever languages, frameworks or runtimes we need.

If, however, we are considering moving an application from a more Platform-as-a-Service capability such AWS Lambda we need to look at the programming model required to move its equivalent in Azure – Azure Functions. While AWS Lambda and Azure Functions are functionally the same (no pun intended) we cannot simply take our Lambda code and drop it into an Azure Function and have it work. It may not even make sense to utilise Azure Functions depending on what you are shifting.

It’s also important to consider the differences in the availability models in use today in AWS and Azure. AWS uses Availability Zones to help you manage the uptime of your application and it’s components. In Azure we manage availability at two levels – locally via Availability Sets and then geographically through use of Regions. As these models differ it’s an important area to consider for any migration.

Tools are good, but are no magic wand

Microsoft provides a way to migrate AWS EC2 instances to Azure using Azure Site Recovery (ASR) and while there are many tools for on-prem to cloud migrations and for multi-cloud management, they mostly steer away from actual migration between cloud providers.

Kloud specialises in assessing application readiness for cloud migrations (and then helping with the migration), and we’ve found inter-cloud migration is no different – understanding the integration points an application has and the SLAs it must meet are a big part of planning what your target cloud architecture will look like. Taking into consideration underlying platform services in use is also key as we can see from the previous section.

If you’re re-platforming an application you’ve built or maintain in-house, make sure to review your existing deployment processes to leverage features available to you for modern Continuous Deployment (CD) scenarios which are certainly a strength of Azure.

Data has a gravitational pull

The modern application world is entirely a data-driven one. One advantage to cloud platforms is the logically bottomless pit of storage you have at your disposal. This presents a challenge, though, when moving providers where you may have spent years building data stores containing Terabytes or Petabytes of data. How do you handle this when moving? There are a few strategies to consider:

  • Leave it where it is: you may decide that you don’t need all the data you have to be immediately available. Clearly this option requires you to continue to manage multiple clouds but may make economic sense.
  • Migrate via physical shipping: AWS provides Snowball as a way to extract data out of AWS without needing to pull it over a network connection. If your solution allows it you could ship your data out of AWS to a physical location, extract that data, and then prepare it for import into Azure, either over a network connection using ExpressRoute or through the Azure Import/Export service.
  • Migrate via logical transfer: you may have access to a service such as Equinix’s Cloud Exchange that allows you to provision inter-connects between cloud and other network providers. If so, you may consider using this as your migration enabler. Ensure you consider how much data you will transfer and what, if any, impact the data transfer might have on existing network services.

Outside of the above strategies on transferring of data, perhaps you can consider a staged migration where you only bring across chunks of data as required and potentially let older data expire over time. The type and use of data obviously impacts on which approach to take.

Clear as…

Hopefully this post has provided a bit more clarity around what you need to consider when migrating resources from AWS to Azure. What’s been your experience? Feel free to leave comments if you have feedback or recommendations based on the paths you’ve followed.

Happy dragon slaying!

Category:
Amazon Web Services, Azure Infrastructure
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