On-premises to cloud migration: The fundamentals
Cloud migration is the movement of data, applications, and other IT services into the cloud. In this piece, we're mainly discussing on-premises to cloud migration — i.e., the transfer of the data hosted in your in-house data center and other infrastructure to an infrastructure-as-a-service (IaaS) or platform-as-a-service (PaaS) cloud deployment. But "cloud migration" is sometimes used to describe moving data from one cloud to another, either within the context of a multi-cloud system or, in some cases, to an entirely different deployment.
During a migration, on-premises data will typically be transferred either to a single public cloud, a multi-cloud service, or a hybrid cloud solution that leverages public cloud resources alongside private on-premises data infrastructure.
The 4 types of cloud migration
There are several approaches to cloud migration strategy, and the choice you make will be contingent on your specific business needs. How much of your enterprise's data needs to be migrated into the cloud? Several hundred gigabytes? A dozen terabytes? Is this your first migration? Answering these questions will help determine the best cloud migration strategy for your organization.
- Rehosting: Also commonly known as the "lift-and-shift" or "forklift migration" approach, rehosting is the simplest type of on-premises to cloud migration. Applications, data, schema, and workloads are moved from the data center to an IaaS cloud deployment, without being changed in any way. While this type of migration is fairly easy to accomplish, it limits what you can do with your apps because they haven't been modified to be cloud-native. It's best suited for select low-impact, on-premises workloads, or as the initial migration method for organizations new to the cloud.
- Refactoring: This strategy, sometimes called "rip and replace" or "redesign," is much more labor- and time-intensive than rehosting. It entails rewriting and restructuring the architecture of apps — and, potentially, data and schemas — either before or after migration; post-migration is more common. The key benefit of refactoring is that you essentially redesign apps from the ground up with the cloud in mind, taking advantage of the latest, most advanced features your cloud service provider (CSP) has to offer. Initial cloud migration costs may be higher, but in the long run, your cloud tools will run more effectively. If you intend to move a lot of your apps and workloads off-premises, refactoring may ultimately be the best choice.
- Replatforming: Falling somewhere between rehosting and refactoring, replatforming involves making some changes to an application while keeping some of its other core elements. Because of this, it's sometimes referred to as "move and improve," or "revise." A common example would be modifying the way in which an app interacts with the database. Replatforming can work for migrations from on-premises infrastructure to IaaS, as well as moves to a PaaS service.
- Replacing: In this migration strategy, data is taken from existing on-premises applications and moved to cloud-based software-as-a-service (SaaS) apps created by third parties, while the original in-house apps are discarded. This approach may make sense for enterprises that have had their apps compromised in some way or are simply working with legacy tools that they consider inferior to third-party SaaS options.
Benefits of migrating to the cloud from on-premises
Enterprises make the choice to shift their apps and workloads from on-premises data centers to cloud infrastructure for many reasons. Sometimes it's based on a general desire to take advantage of the cloud's virtually limitless storage. In other instances, organizations are looking to meet specific needs, like facilitating better, more flexible working environments for DevOps.
That said, there are several key advantages that the vast majority of organizations are hoping to enjoy as a result of their cloud migration:
Increase accessibility
Today's enterprises exist in a cloud-first business world. And with a great number of businesses having their workforces distributed across disparate locations — often while working from home or in other non-office settings — it's critical for employees to have always-on access to critical apps and data no matter where they are. Leveraging public cloud resources gives enterprises the assurance that location won't be an impediment to personnel getting their work done.
Improve performance and agility
The ability to run applications anywhere isn't as valuable if they run slowly or function improperly. When workloads have been migrated to the cloud from on-premises infrastructure, this is less likely to happen, as the major CSPs have cloud data centers all over the world to reduce latency for their customers' operations.
Additionally, migrating to the cloud makes it much easier for growing businesses to adjust and add resources as needed. This includes everything from new SaaS tools from CSPs or third-party vendors to apps developed in-house.
Leverage elasticity and scalability
Enterprises face sudden spikes in resource needs on a fairly regular basis: sometimes for minutes or hours, other times for weeks or months. The cloud's elasticity and scalability allows you to address short-term surges by dynamically expanding compute, memory, and storage capabilities when necessary and contracting them when need passes. You can also add and subtract new resources as business demands require. This is an advantage that on-premises operations can't match in terms of pace.
Achieve cost efficiency
The cloud's aforementioned elasticity and scalability also allow it to offer greater cost efficiency in numerous ways. For example, scaling up on-premises infrastructure is going to be more expensive than comparative cloud costs no matter what, and scaling down is arguably even more costly. Also, making cloud usage an ongoing cost of doing business allows for more efficient budgeting and spending in the long term.
Support security and compliance
Major CSPs, especially the "big three" of AWS, Azure, and Google Cloud, offer numerous cloud-native security features, quite possibly beyond what you have on-premises. This can allow you to adhere to compliance requirements for data workloads subject to strict security regulations. If your enterprise opts for a multi-cloud deployment, you can even devote one or more of your clouds specifically to those workloads.
5 steps for a successful cloud migration from on-premises infrastructure
No two migration projects are alike. However, generally speaking, the following five steps will serve any enterprise well in their efforts to migrate from on-premises to the cloud:
- Make a plan: A successful cloud migration starts with answering two questions. Why do you want to migrate data and apps to the cloud? What will you be migrating? This will determine how complex the operation will be: For example, using the cloud for disaster recovery of a small number of apps will be less intricate and involve fewer steps than a complete transfer of enterprise workloads. Similarly, if DevOps is your main motivation, you'll know that migration to PaaS may be a better choice than IaaS. A complete inventory of existing applications and reports is also critical, to identify unused or duplicate reports and data that hasn't been accessed and avoid the extra work of migrating those items.
- Do your due diligence: Investigate the offerings of different vendors to get a sense of what your total cost of ownership (TCO) will be in each case. You'll also want to consider the logistics and resourcing requirements for different migration strategies. Keep in mind: There's no harm in starting small with on-premises to cloud migration — e.g., an initial lift-and-shift operation for some app workloads — and trying a different strategy like replatforming or refactoring later on, when you have a better idea of what you need from the cloud.
- Prep your security: Deploy a cloud firewall-as-a-service (FWaaS) in advance of your actual migration to minimize exposure of on-premises data while in transit.
- Start small: Begin the migration by moving a workload that isn't mission-critical to enterprise operations in real time, and test its cloud functionality. Once you're sure the app and data are in order up in the cloud, continue the migration according to the strategy you've decided. Business operations can be delayed during the process, especially in refactoring migrations that are not thoroughly planned and tested in advanced. Most cloud providers offer tools that help mitigate the disruption.
- Keep improving: Carefully sync and update apps as needed once migration is complete. If you're doing a cloud-only migration, on-premises systems can be disabled. But there are many situations in which retaining these systems will be valuable, such as a hybrid cloud deployment.
On-premises to cloud migration challenges to overcome
Embracing the possibilities of the latest cloud trends through an on-premises to cloud migration is not without potential challenges. With careful planning and the right partners, you can avoid these obstacles:
- Cost overruns: Migration-related expenses and TCO, bandwidth needs, resource allocation, and ongoing post-migration costs can add up quickly. Careful planning in advance is of the essence.
- Databases: In some cases, migrating on-premises databases to the cloud is much slower than transferring app workloads, but it doesn't have to be that way. Your cloud vendor rep and IT team can collaborate and find ways to mitigate any operational disruptions caused by an on-premises to cloud migration.
- Legacy infrastructure and apps: Some legacy systems were developed before the advent of cloud computing. Most can be migrated, but it's crucial to think ahead. During the planning stage, determine whether legacy resources should be replatformed, refactored, or replaced before migration.
- Security: Both pre- and post-migration CSPs provide security for cloud infrastructure — not your workloads and data. This is why deploying and maintaining a cloud FWaaS is so important for both your cloud resources and any on-premises infrastructure you maintain, as it protects both.
Teradata's approach to data migration can help you circumvent the difficulties that may arise during the process, particularly when moving databases to the cloud. Through a combination of thorough consulting, automation, data unification, and data model integration, Teradata Vantage and other tools can help you execute a successful migration, with a better understanding of your data and cloud infrastructure.
Learn more about cloud migration strategies