Migrating from VMware to KVM: The Right Data Storage Matters

In the realm of information technology, change is a constant companion. As IT teams seek more cost-effective and flexible solutions, the migration from VMware to KVM (Kernel-based Virtual Machine) has gained traction. This evolution goes beyond software choices; it extends to critical elements like block data storage, redefining how organizations approach virtualization and data management.

The Foundation of Virtualization: Data Storage

Before delving into the migration journey, it’s essential to understand the pivotal role that data storage plays in virtualization. In traditional setups, data storage is coupled tightly with the hypervisor – a role VMware has excelled in. However, as the virtualization landscape evolves, the demand for open-source, customizable solutions, like KVM, are on the rise.

The KVM Advantage in Data Storage

Central to KVM’s appeal is its efficient utilization of block data storage. Unlike file-based storage, where each virtual disk is stored in a separate file, block-based storage treats each virtual disk as a raw block device. This distinction opens up new possibilities and benefits for IT teams making the transition.

1. Performance Boost:

Block storage’s direct interaction with raw disk devices leads to enhanced performance, particularly for I/O-intensive workloads. KVM’s integration with the Linux kernel further streamlines data access, minimizing overhead and delivering efficient performance gains.

2. Flexibility and Customization:

Block storage offers greater flexibility in terms of storage solutions. IT organizations can leverage various storage technologies, such as SAN (Storage Area Network) or iSCSI (Internet Small Computer System Interface), or StorPool native protocol tailored to their specific requirements. In addition, KVM is the default virtualization architecture for cloud or virtualization management platforms such as OpenStack, CloudStack, Proxmox, and OpenNebula that provide the flexible, customizable workflows modern IT demands. Integrations between the CMPs and storage platforms allow IT teams to optimize and customize storage configurations according to workload demands.

3. Improved Scalability:

Block-based storage enhances the scalability of virtualized environments. As IT teams migrate from VMware to KVM, they can seamlessly integrate their existing block storage systems, ensuring smooth scalability as workloads grow. Highly scalable block storage solutions can complement this compute scalability providing additional flexibility.

4. Data Integrity and Management:

Block storage’s direct interaction with disk devices facilitates better data integrity and management. This is particularly valuable for critical applications and databases that require stringent control over data consistency and reliability.

5. Snapshot Capabilities:

KVM’s utilization of block storage makes it easier to create and manage snapshots of virtual machines. These snapshots are vital for data backup, recovery, and testing without affecting the production environment.

6. Open-Source vs. Proprietary

Many IT organizations prefer open-source solutions to proprietary licensed software for a variety of reasons from cost to source access to philosophical reasons. VMware has recently been acquired by Broadcom which has left partners and customers concerned about the future of VMware products and services. While open-source software often has corporate sponsors whose level of investment changes over time, the software itself will always continue to be available even if the sponsoring company chooses to discontinue its support.

Challenges and Considerations when Migrating Block Data Storage from VMware to KVM

While the benefits are clear, migrating block data storage from VMware to KVM involves several considerations and challenges:

1. Data Transfer and Conversion:

Moving block data storage requires careful planning to ensure data integrity. Tools like virt-v2v aid in converting VMware VMs to formats compatible with KVM. It’s essential to verify compatibility and perform thorough testing after migration.

2. Storage Protocol Compatibility:

Ensuring compatibility between the storage protocols used by VMware and KVM is crucial. Proper configuration of protocols like iSCSI or NFS (Network File System) is necessary to maintain seamless data access. 

3. Performance Optimization:

As you migrate block data storage, take the opportunity to optimize storage configurations. Align storage performance with the unique requirements of your virtualized workloads to achieve maximum efficiency. If your current storage has become a bottleneck, your KVM migration may be an opportune time to consider new kinds of block storage solutions including software-defined solutions providing agility and scalability along with high performance.

4. Resource Allocation:

During migration, allocate sufficient resources for storage systems in the KVM environment. This includes disk space, I/O bandwidth, and provisioning for future growth. Highly scalable storage architectures can be a good solution allowing you to migrate virtual machines at your own speed, adding capacity to your storage solution as you need it.

5. Backup and Disaster Recovery:

Update your backup and disaster recovery strategies to accommodate the changes in storage infrastructure. Ensure that snapshots and data protection mechanisms are in place to safeguard critical data. 

6. Management Platforms

The VMware ecosystem provides robust management tools for your virtual machines. Ensure that the new virtualization or CMP tools meet your needs and align with your skill sets and desired workflows.

Seizing the Future: Embracing KVM and Block Data Storage

The migration from VMware to KVM, with a focus on block data storage, represents a strategic shift that underscores an organization’s adaptability and innovation. As virtualization technologies evolve, IT teams must stay ahead of the curve to remain competitive.

In this journey, IT teams should follow a systematic approach:

  • Assessment and Planning: Evaluate the existing storage infrastructure and requirements. Plan the migration meticulously, considering compatibility and performance.
  • Testing and Validation: Thoroughly test the migrated storage systems and virtual machines. Address any issues before they impact the production environment.
  • Performance Optimization: Fine-tune storage configurations to ensure optimal performance for different workloads.
  • Resource Management: Allocate sufficient resources for storage systems and monitor their utilization to prevent bottlenecks.
  • Backup and Recovery: Update backup and recovery strategies to align with the new storage environment. Regularly test recovery processes to ensure data integrity.
  • Support and Maintenance: Ensure that teams are trained to maintain and support the new system and that support services are in place for your virtual machine servers as well as your storage platform.


The migration from VMware to KVM is not just a change in virtualization platforms; it’s a paradigm shift that empowers organizations to tailor their IT environments to their unique needs. Block data storage, as a fundamental pillar of this transformation, amplifies the benefits of KVM’s open-source and customizable approach.

As IT teams navigate this migration journey, they should approach it with careful planning, technical expertise, and an eye toward the future. By embracing KVM and harnessing the power of block data storage, organizations position themselves for a more agile, adaptable, and efficient virtualization ecosystem. StorPool has helped many organizations through this process, from project planning, to architecture design to data migration, to performance tuning and continuous support. We can help you too. 

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