Cloud Migration

Abimuktheeswaran Chidambaram
7 min readJun 6, 2023

Cloud migration is the process of moving digital business operations like data, applications, IT processes from on-premises to the cloud. Sometimes it may be from cloud to cloud.

Benefits of Cloud Migration:

Performance, Scalability, cost reduction, Flexibility, Shift everything as a service.

  1. Phases of Cloud Migration: The following phases in cloud migration are Prepare, Plan, Migrate, Operate, and Optimize.

Prepare — Evaluate the current data center environment and its suitability for a move to a cloud architecture. Deploying automated tools to gather information can significantly speed up this process. To properly plan your migration, you need to identify the workloads that are to be migrated and which cloud computing model best fits your needs.

Plan —Once an organization has established its business objectives and evaluated its cloud readiness, the next phase is to create a detailed migration plan. This plan should include a roadmap for the migration process, detailing which workloads will be migrated and in what order. Organizations should also decide on their preferred cloud architecture and identify any necessary modifications to their existing applications or data. This phase is also the time to address any compliance or security requirements related to the migration.

You use the gathered information in the preparation phase regarding migration. In this phase you may choose which type of strategy is suitable for your needs also choosing vendors & deploying models while migration.


After you complete migration planning and identify a migration strategy, the actual migration takes place. In this phase, the target database is designed, the source data is migrated to the target, and the data is validated.

Operate and Optimize — When your database is in AWS, you have to operate it in the cloud. You need to make sure that you are following the best practices for areas such as monitoring, alerting, backups, and high availability. The operation overhead of rehosted databases is higher than the databases that have been re-platformed or refactored to use a managed AWS database service.

2. Strategies of Cloud Migration

  • Rehost ( Lift and Shift ) — You can deploy your existing data from the source environment to the cloud using IAAS. It is suitable for those who are less familiar with the cloud environment and have difficulty in modifying code. The advantages of Rehost are No changes in code or architecture, an Easy and speedy migration process, and easier compliance and security management. Disadvantages of Rehost are can’t to map the failures accurately, increased risk, latency, and performance issues due to not optimizing for the cloud environment.
  • Relocate — It is the same as Rehost, additionally, it enables you to create a virtual copy of your data center.
  • Replatforming ( lift-tinker and shift ) — Using IaaS the core structure of the application has not changed, But the remaining parts may change.
  • Refactoring / Re-architecturing — Using PaaS the core part of the application may change. you can choose partial or complete re-factor depending upon your needs.
  • Repurchasing / Replacing — Using SaaS moving to a different product.
  • Retain (Revisit) — You can keep your applications in your source environment. It means you are not ready to migrate currently. In the future, you may need to migrate to the cloud.
  • Retire — IT Assets and services are no longer needed. They can be shut down(or) moved to the archive. So the business can focus on services to improve.

3. Types of Migration

3.1 Database Migration means moving data from the source database to the target database using AWS Database Migration Service (DMS). You can’t use AWS DMS to migrate from an on-premises database to another on-premises database. Here are some terminologies of DMS

  • homogeneous migration- A migration from source databases to target databases where the source and target databases are of the same database management system. Ex: Oracle to Oracle.
  • heterogeneous migration — A migration from source databases to target databases where the source and target databases are of the different database management systems. Ex: Oracle to MSSQL.
  • Database Replication — transfer of data from source DB to target DB without shutting down the source DB after the migration completes. To improve high availability it is shared with all. This results in a Distributed database.
  • Schema Conversion Tool — convert the data from source DB to target DB when it is a heterogeneous migration. Database Schema is a blueprint of the database it contains field names, data types, relationship entities, etc., not the data.
  • Database Discovery — If you don’t know your source DB in your source environment you can use DMS fleet advisor. It collects and analyzes the data in your source environment within a few hours without the use 3rd party tools and helps to migrate automatically.
  • AWS announced the “AWS DMS serverless“ feature to automate manual work like provisioning, estimating, monitoring, scaling, etc. You may start the migration within a few hours and also save money for data migration resources only. It is suitable for complex database projects and ongoing data replication. DMS Serverless supports both Single-AZ and Multi-AZ deployment options.

For more details about AWS DMS click here

3.2 Storage Migration means moving data from your source environment to the cloud either online or offline. Object storage, Block storage, and file storage are the three types of storage in AWS. AWS recommends “ snow family “ and “Transfer family “.

3.2.1 AWS Transfer Family uses the following protocols to transfer the files over the protocols ( SFTP, FTFP, FTP, A2A) directly to (or) from AWS.

  • SFTP (Secure shell File Transfer Protocol over SSH) — suitable for sending large files from server to server. It has a pause and resume feature. It supports authentication not for certificates. More secure and slower than FTPS.It operates on port 22. Certificates are not supported.
  • FTPS ( File Transfer Protocol over SSL) — suitable for sending small files from server to client and vice versa within a local network. Less secure and faster than SFTP. It has identified the correct error feature. Certificates are supported not authentication. It operates on port 69. It uses TLS and SSL to encrypt traffic.
  • AS2 ( Applicability Statement 2) is a file transfer protocol (HTTP-based) from server to server for data exchange between trading partners over the internet. It is associated with Electronic Data Interchange(using digital transactions instead of paper).

3.2.2 AWS Snow Family has a snowball, snow cone, and snowmobile. It is a storage migration device. It looks like a suitcase designed for maximum portability. It can work offline by shipping the device (or) in online means by using AWS DataSync. Once a device arrives, you connect it to your local network and set the IP address either manually or automatically with DHCP. Data copied to the device is automatically encrypted and stored in the buckets you specify. It works with wired and wireless networking. You can receive tracking status using AWS SNS. After the migration is completed and the entire job is done AWS securely erases the data. Use AWS OPShub to set up and manage the snow device for migration. You can’t migrate the data from region to region using snow devices.

Snow Cone is a storage migration device. It has 2 device types, they are Snow Cone HDD have 8 TB of usable storage and Snow Cone SSD have 16 TB of usable storage.

Snow Cone Device

Snow Ball Storage capacity is 50TB and 80TB. But these are now out of service so they are using Snowball Edge instead of Snow Ball. The Snowball Edge Compute Optimized version provides higher computing capabilities and is designed for high-performance workloads. The Snowball Edge Storage Optimized version provides more storage capacity (Storage capacity is 80TB and 210TB), networking connectivity (10GB,40GB,100GB ) and it’s designed for large-scale data migrations and capacity-intensive workloads. To migrate less than 10 PB of data sets you can use a snowmobile.

Snow Mobile can transfer up to 100 PB of data. To migrate more than 10 PB of data sets you can use a snowmobile. The Data transfer rate is 1 TB per second.

3.3 Application Migration:

AWS Application Migration Service is normally as cloud migration. It is 90 days free. After 90 days it will be charged on an hourly basis. To avoid public connectivity you can also choose private connectivity such as VPN, VPC Peering, AWS Directconnect, etc. Your data is encrypted and secure while moving from source to destination using TLS 1.2 protocol and AES-256 bit encryption. After it moves to the destination it uses EBS encryption.

Last Updated: 07-Jan-2024