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Rahul Mathur
Rahul Mathur

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A Complete Guide for Migration of Legacy Systems to Cloud with new a stack

Cloud computing solutions

In the digital era, every application is available at our fingertips. We can use these applications at the time of traveling by Air, by Bus, by train or in any city or country. Users can access, upload, or delete their data from anywhere. If today we compare technology with the old days, we can analyze how technology changed and transform our life.

In last 2 decades, the Cloud computing has disrupted the technology paradigm, it has accelerated the business growth and has attained the Technological pivotal position for organizations, which want to manage their resources and offer them a niche competitive edge. Currently, most of the organizations have incorporated a certain degree of cloud computing into their Enterprise and Business applications, but they are still using ageing legacy software systems, which incur a higher degree of risk and migrations complexities. Until and unless you have a brand-new start-up, you are most likely running a certain level of legacy platform and systems, which need to be migrated to the Cloud to avail all the benefits of cloud technology.

Legacy application is nothing, but a customized application developed by internal development team to cater a specific requirement of the organizations. An organization faces multiple risks while executing a migration from an in-premises server to the cloud, and it is desired to have a minimum impact on business performance and resources while conducting the transition. In this article, we will discuss about Cloud technology, its advantages and disadvantages, steps of migration of legacy systems to cloud etc.

What is Migration:

The meaning of migration, in general, is moving from one place to another, in Information Technology migration is the same only changes here word place to environment or Technology platform. When we move any application from one platform to another platform or one environment to another environment it is called Application Migration.

Migration meaning moving the existing technology platform to a new Platform without impacting existing users and their application. Application, Database, or Hardware all can be migrated.

Migration Types:

There are few types of Migration, such as:

1. Database Migration: Moving old database data (tables) into new database tables called database migration. The format of the data in both databases will be the same and the only thing which changes the new database management technique.
There are various tools like Qlik Replicate, Oracle Golden gate, Informatica, etc. which uses for data migration.
Some point keeps in mind while doing Database migration:
• Always take a backup of the current database
• Always take long downtime

2. Application Migration: Moving one application from one platform to another called application migration. Here platform can be on-premises to cloud and while moving to the cloud it is important to know the security provided by the cloud provider.
3. Cloud to Cloud: Cloud to cloud migration is a new type of migration and popular these days. Cloud migration saves the cost of infrastructure cost and space. It also runs on commodity hardware. To manage these types of systems we only need a Good Internet connection and commodity hardware.

What Are Legacy systems?

Legacy systems are older software or hardware which are companies still using. These types of systems are capable to run the application but do capable enough to meet/interact with the latest technologies and many more.

Why companies still using legacy systems?

Organizations use legacy systems due to several reasons.

1. Cost- Legacy systems are expensive over time but moving from legacy to the cloud is also a bit expansive and required skilled manpower which increases the overall operation cost of a company.
2. Maintenance issues- Legacy systems are work on very old technology and skilled people on those technologies are very less so if we talk about maintenance about these old systems so it is very difficult and it required hard to find manpower with so much cost.
3. Integration Difficulties- legacy systems are not designed to integrate extensively with other application so data resides under the storage box and less integrate with other applications
4. Data Compliance difficult- In legacy systems, it is very difficult to know in which storage section data resides, so it creates a compliance issue for different customers.
5. Security concerns- legacy systems are so vulnerable to third party apps. If we compare today’s application, it comes with multiple layers of security with encryption, but older systems do not have many capabilities to prevent the attacks. Legacy systems are not only less secure but very risky for customer data. These types of risks can damage company value and its customers.

What is Cloud?

For new readers, it is very important to explain the basics of the cloud. Cloud is a combination of servers resides in some data centres over the world and accessible via the internet. The software and databases run on those servers also accessible via the internet anywhere at any time on any device. Users need to rent or buy the resources of the servers and deploy the application or database on those servers. There are some cloud service models which used very extensively.

1. Software-as-a-Service (SaaS): installing the software on multiple devices, buying the license of that software is a very difficult and time taking process so to overcome this problem, we can use Software-as-a-Service (SaaS). In this model, the user-hosted his/her application on the cloud and use it over the internet. For example, suppose someone has created some chat application and hosted it to google cloud or Microsoft cloud now he/she could sell their application to multiple customers and pay some dollar amount to google or Microsoft to using their cloud servers.

2. Platform-as-a-Service (PaaS): The application development is a very creative and time taking process and for that, you need to buy resources like development tools, operating systems, infrastructure from different places but using the Platform-as-a-Service (PaaS) model we don’t need to buy the different resources. In this model, cloud services companies provide everything in a single place to build the application on the cloud and access it via the internet example, Microsoft Azure.

3. Infrastructure-as-a-Service (IaaS): To run any application company need hardware resources like Servers, Storage, RAM, etc. so in Infrastructure-as-a-Service (IaaS) model cloud providers provide the resources like servers and storage to the company to run the application.

Cloud Deployment

Every organization has multiple departments and for some department, data security is so much required whereas for other department data can be shared so for different type of environment the cloud deployment model changed and the type of deployment models are below:
1. Private Cloud: In this type of deployment organization owe private datacentre, Server, or Distributed network dedicatedly and those cloud servers are not shared with other organizations
2. Public Cloud: in this type of deployment the cloud server is distributed with multiple organizations via virtual machine. This concept is known as multitenancy, as it allows multiple tenants to use the shared server space within the same server.
3. Hybrid cloud:Hybrid cloud is a combination of Private Cloud and Public cloud and sometimes it also includes the legacy systems. As I explained above example some application runs on a private cloud and some on the public cloud.
4. Multiload: The combination of multiple public clouds is called multi-cloud. In multi-cloud within a group of the server, multiple resources are shared with different users. In multi cloud multiple virtual machines are working together and different user access those multiple machines.

Advantages of the cloud

As of now, we have seen the cloud models and deployment types of the cloud. Now we have some strong advantages of cloud technology and these advantages are:
1. Cost: Moving to the cloud saves infrastructure and the IT operation cost. It will also save maintenance time and cost. Due to the cloud company can run their business 24*7 without thinking about the application down or network issue.
2. Scalability: The biggest advantage of cloud computing is Scalability. Suppose we’ve deployed some application of cloud and as a systems admin we observed that the load of the user increasing so using cloud we can increase the hardware resources to balance the load of the users without changing existing applications and no need to buy new hardware.
3. Performance: Cloud technology also increases the performance of the application. Suppose we have hosted some websites on the cloud platform so that the request and response time decreases, and the user can access the data so fast.
4. Flexibility: Cloud technology also provides flexibility to the organization to operate from anywhere. It also provides a hassle-free experience to organizations customers. It also helps the organization to expand its business without thinking about the infrastructure.
5. Zero Downtime: Using cloud application there is no downtime of the applications. It gives business strength to operate very fast and accurate. Earlier when we need to update the application or hardware, we used to take long hours of backup, and then we used to take downtime to apply the fix of the application. While applying the fix sometime applications data corrupted and again, we need to roll back the backup, so these all things take so much time and effort. All these issues are solved by cloud technology.
6. Best for SMB and Mid customers: Small and medium customers have very limited capital to operate and It is very difficult for them to buy a server and set up a datacentre so for those companies’ cloud helps a lot and solves the infrastructure problem very well

Challenges of Cloud technology

There are some advantages of cloud technology and some challenges also. These challenges occur when we migrate from legacy to cloud.

• Challenges with large databases: If we think to migrate some databases from one premise to another it will take so much time and effort. Moving databases to the cloud is a very difficult task and especially when the data is so large. Moving large data through the internet is the very challenging task so to overcome these issues some migration tool helps a lot in it.

For example, Qlik Replicate is one of the most important tools for migrating data from legacy to cloud. This tool has a very simple User Interface and amazing features like Change Data capture and stores change functionality which always makes the sync between source and destination systems.
This tool also has Full load functionality to snapshot the one database and transfer the whole database table and schema to the cloud database.

• Data solidarity: It is very important data integrity and solidarity while transferring the data through the internet. It should be secure and safe.

• Trust Issues: Still some country's governments do not trust cloud technology and work with legacy systems. The main reason for not trusting cloud is the data is so confidential and they think the data is on the internet and any hacker can steal it.

Steps to migrate an On-Premises Legacy System to Cloud

There are few steps which help an organization to move a Legacy or on-premises system to Cloud.

1. Conduct an audit – Before executing a Cloud transition, we must understand legacy business system performance and how it is being used. We have to make a comprehensive list of our on-premises systems, infrastructure, resources, and applications.
We must evaluate the status of each legacy system, whether is it Cloud friendly or will it require any sort of re-engineering to make it compatible with the cloud environment. We must conduct a thorough audit to understand the desired output, its value, and the proposed cost to be incurred, because sometimes it is not worth to upgrade or migrate all the systems or applications to cloud. In this audit step, we may uncover several systems, applications and platforms that may not hold any business value, such entities could be retired.
This is a crucial step and it involves the activity to map the relationships between the legacy systems and other resources. This mapping will help us identify systems that can be merged and can be moved together, and those as well which should not be moved together. Identification of dependencies combined, and those that should not be moved without another. Conducting this audit and Identifying dependencies will ensure minimum disruption while migration to Cloud.

2. Onboard the Team – It is obvious and essential to form a team and get all the resources on board to ensure we have adequate support available to carry out the migration. The team will help us in the identification of application they are using and the associated problems and risks with them. This step will help us identify the potential problems and risks that may pose a threat in the new Cloud environment. In this step, we also identify the integration points of existing legacy systems and any possible workarounds.

Step 3: Assess the Microservices options- Once we have completed the audit, dependencies, topologies and other mappings, it is time to assess and decide, we will have to decide the cloud requirements, so that we can adequately assess the available cloud options. Here the information collected in last 2 stages comes handy and help us taking the right information.
Here we must keep the following things in mind:
• We should have testing plans in place, along with Operating System, Server, and Database.
• The CPU, Memory, Storage and Network requirements.
• The sensitivity of the information, which is supposed to be migrated, and its access data over public and secure connections.
• Proposed cost of cloud computing and other resources.
• The type of services we are offering and the nature of the industry we are working in.
• Security concerns while moving out of an on-premises data centre to a 3rd Party cloud platforms (AWS, Azure or Google). It is important to identify the access levels, authentication requirements, role-based access, encryption requirements.
• Assessment of bandwidth and cost of each legacy system should be thoroughly conducted. A cost benefit analysis should be performed to understand if a legacy system migration is practically and financially viable.
• A thorough assessment of regulatory, compliance and financial dependencies, to avoid any issues at later stage. A 3rd party cloud vendor should be selected based on this analysis, who should have a proven track record for a specific service sector or domain.
• Once we have all the information in place, a correct Cloud vendor could be selected, who can fulfil the enterprise requirements and offer the cloud-based services to our organization, like PaaS, SaaS, or IaaS.

4. Get your Legacy Systems Cloud ready – It is important to modularizing the architecture of the Legacy system, to ensure it is compatible with the native cloud services. Some legacy systems may follow the simple ‘lift and shift’ approach, whereas other systems could need a certain level of re-engineering or change in the architecture to make them cloud ready. We must understand the proposed cloud service hierarchy and its alignment with the legacy system we are attempting to migrate. Some legacy systems may work efficiently with certain services, and some processes may pose challenges.
For example, if we want to move a legacy corporate email system to a public cloud service like Microsoft’s Office 365, then it could be achieved by using the off-the-shelf software. This is called as ‘lift and shift’ approach.
However, the similar approach cannot be implemented with an internal legacy application, which is heavily customized to perform a specific kind of task. There we must perform a certain degree of re-engineering and re-structuring to make that legacy system cloud ready.

5. Develop a migration plan with phases – Migration is an experimental process, when we are migrating a legacy system to a whole new cloud ecosystem, in iterative manner, it helps us to avoid developing on a flawed idea or code.
It is always believed that the most effective method for conducting the legacy system migration should be in incremental manner. The phased plan ensures ensure minimal disruption to the organization’s operating and business continuity. It is always recommended to conduct a thorough assessment of the changes proposed in the internal business processes.
Migration could be started with the simpler applications and system components, and then we can proceed with the complex components in a phased manner. We can choose non-complex system first, as that will offer a high chance of success. Finding small issues in the legacy systems as you incrementally release is always better than finding complex problems on actual launch.

6. Proceed with migration – This is the actual phase of the migration, where we shift the legacy system to the Cloud environment. Here the initial release of your system should be the minimum viable product. It will allow us to implement a build, measure, and learn approach. This is most critical stage and it requires a closed cooperation of all the teams involved.

Some strategic tips while executing the cloud migration:

  1. Always migrate the existing data or create some initial data on the cloud.
  2. Whatever tool we are using for replication, but the replication should be continuously or ongoing.
  3. Once the source systems and destination systems in sync then move business intelligence.
  4. Now the time to move the legacy data application to the cloud and give some time to sync up with the existing data.
  5. Once the application settles down now, we can start moving our older ETL process to the cloud and it should extract the data and load it similarly like a legacy.
  6. Once everything is migrated to the cloud, the last part is testing the new application. To test the new cloud application, we can increase the dummy requests on the application and observe how the application is responding.
  7. We can check with real-time user load also. If users can see their data without any problem and the application is working at an optimum level, then we can say that the migration is successful.
  8. Replace the old with New SaaS (Software as a service): If any business running on legacy technology then they can discard the old technology and move to SaaS-based technology it will help them without investing much in infrastructure.
  9. By creating the same solution on the cloud: Suppose an organization have some infrastructure on prim so creating the same configuration on cloud help them to work similarly or even batter
  10. Rebuilding: Rewriting and redesigning the whole application from scratch help the organization to achieve the goal.


As we have seen above, migration of a legacy system to a cloud environment is certainly not an easy task. It is time consuming and at the same time, it involves a higher degree of risk and challenges. It may put a negative impact on the business performance of the legacy systems during the transition period.

We are pretty much sure that if you follow the steps above, you may have lesser chances that your legacy cloud migration will be unsuccessful. It is also advisable to perform the analysis and assessment in correct way and conduct the testing with complete integrity, as it will ensure we will not face any challenges later. It is also advised to follow a scientific and logical approach, which indeed help the business in long term. We must use model-driven approach to make the migration process efficient and highly flexible.

It is also advised to always keep in mind, that never underestimate the extent of the problems and risks if you encounter one. We have to define the Key Performance Indicators (KPI), that can help us keeping a check on the migration process and several metrics associated with it.

In the end, all we can say that migration of Legacy system appears to be a complex and daunting task, but it has become a necessity these days. So, always make sure that you perform the migration of legacy system to Cloud environment and we are sure that the above mentioned comprehensive steps can assist you in the migration of legacy system to cloud easily.

Top comments (1)

liligrvs profile image

What are legacy systems?Today, an astounding 80% of businesses are burdened with legacy systems that hamper innovation and hinder digital transformation efforts. Legacy systems are the aging relics of technology, encompassing outdated hardware and software applications that have become increasingly obsolete. Despite this obsolescence, many organizations still rely on them. This can include outdated hardware as well as software applications and programming languages. Here are some examples of how companies have benefited from legacy modernization: