VMware Migration: Cold Migration vs. Live Migration – Recommended Scenarios and Solutions

With Broadcom’s changes to VMware’s product sales model, many enterprises are exploring VMware migration solutions. When migrating from a VMware environment to another platform, businesses often consider: How can business continuity be ensured? What are the VMware migration guidelines and tools? And what should be noted during the VMware migration process? The key lies in understanding the two primary migration methods—cold migration and live migration—and selecting the one that best suits their business needs. This article delves into the characteristics and applicable scenarios of these two migration approaches and recommends optimized live migration solutions.

VMware Virtual Machine Migration: Core Concepts

Virtual machine migration refers to the process of moving a virtual machine from one host or storage location to another, which differs from cloning or replicating a virtual machine (i.e., creating a new VM). Depending on the virtual machine’s state, migration can be categorized as cold migration or live migration.

Cold Migration: Secure Transfer with Planned Downtime

Cold migration refers to migrating a virtual machine while it is powered off or suspended. This method allows relocating the VM’s configuration and disk files to new storage. Additionally, cold migration can be used to move a VM from one data center to another. Executing a cold migration typically involves manually moving VM files or setting up scheduled tasks.

The advantage of cold migration is that the VM does not need to reside on shared storage, and the risk of data loss is minimal. However, its primary drawback is that the VM must be powered down, resulting in business interruption. In terms of performance impact, cold migration involves noticeable downtime. Although the network transfer phase may consume more bandwidth at once, the entire transfer is completed in a single operation.

Live Migration: Ensuring Business Continuity

Live migration, also known as real-time migration or vMotion (in VMware environments), refers to migrating a VM without interrupting its operation. This method involves very brief downtime, making the process nearly transparent to users. Live migration heavily relies on snapshot technology to ensure data consistency and integrity. Snapshots record the VM’s state at a specific moment, including memory, storage, and device status. Changed Block Tracking (CBT) technology continuously tracks all changes on the virtual disk and applies them to the target location. For memory state migration, many mainstream tools use a pre-copy strategy, cyclically sending dirty memory pages to minimize downtime.

The benefits of live migration are evident: it ensures that software and hardware maintenance or upgrades do not impact critical user services, significantly improving service availability and user satisfaction. It can be used for maintenance, load balancing, co-locating interconnected VMs, separating multiple VMs to minimize fault domains, and migrating to new server hardware, among other scenarios. Compared to cold migration, live migration achieves near-zero downtime, though there may be brief service response delays. During live migration, network resources are consumed to maintain synchronization between the two servers.

Cold Migration vs. Live Migration: In-Depth Analysis of Applicable Scenarios

The choice between cold migration and live migration depends on specific business scenarios and tolerance for service interruption.

Cold migration is suitable for:

Planned hardware maintenance or upgrade activities where brief downtime is acceptable.

Small businesses with limited budgets that may prefer cold migration to save costs.

Situations where a VM and its associated disks need to be moved from one datastore to another.

Live migration is suitable for:

Critical business applications or public-facing services that require uninterrupted operation, where any downtime could result in significant financial loss or customer dissatisfaction.

Enterprises with strict Service Level Agreements (SLAs) that mandate high availability and low latency.

Overloaded physical machines requiring VM migration for load balancing.

Cross-domain environments where resource balancing is needed, such as moving VMs from heavily loaded to lightly loaded physical machines.

Hardware system repairs, upgrades, or software patches where the VMs cannot be powered down.

VMware to ZStack: Seamless Migration and Performance Optimization

Faced with market changes such as soaring VMware product costs, more enterprises are seeking VMware to ZStack solutions. ZStack offers a comprehensive cloud infrastructure solution and provides three primary migration paths: virtualization solutions, private cloud solutions, and hyper-converged infrastructure (HCI) solutions. These solutions have successfully helped over 600 enterprise customers significantly reduce costs.

During the VMware to ZStack migration process, ZStack not only supports traditional live migration features in VMware environments but also offers enhanced capabilities and optimizations.

Efficient Resource Scheduling:

ZStack intelligently identifies system loads and automatically adjusts migration strategies to minimize impact on running tasks.

Seamless Integration:

For hybrid cloud environments, ZStack provides strong compatibility with existing VMware environments, enabling users to perform live migration across platforms effortlessly.

Simplified Management:

With an intuitive graphical interface and automation tools, administrators can execute and monitor migration processes more easily, reducing operational complexity and technical barriers.

Notably, ZStack also supports live migration with SR-IOV (Single Root I/O Virtualization) enabled. SR-IOV is a hardware passthrough technology that allows multiple virtual functions of a physical NIC to be directly assigned to different VMs, bypassing the virtualization layer to significantly improve network performance. With SR-IOV, packet forwarding rate (PPS) performance increases by 2500%, average latency decreases by 60%, and CPU usage drops to 1/7 of its original level. This means that under the same hardware conditions, ZStack combined with SR-IOV delivers substantial performance improvements, making network services more efficient and stable.

ZStack Cloud also includes a built-in virtualization management module that supports integrating existing VMware virtualization resources, making it suitable for gradual transitions to cloud platforms. Additionally, ZStack’s VMware Agentless Migration Solution replicates VMs via transfer servers, offering a non-intrusive approach that effectively reduces operational risks for customers.

ZStack‘s product portfolio covers data center cloud infrastructure, ensuring convenient infrastructure and smooth migration, thereby helping enterprises achieve digital transformation, digital restructuring, and cloud data center construction. For example, the ZStack ZSphere virtualization platform delivers a user experience consistent with VMware virtualization and supports intelligent unified operations and smooth V2V migration, ensuring business security and reliability.

ZStack: Let Every Company Have its Own Cloud

ZStack (Shanghai ZStack Information Technology Co., Ltd.), founded in 2015, is a leading cloud computing technology provider specializing in the R&D of cloud computing software and hardware. It has successfully delivered advanced cloud computing technologies to over 4,000 enterprise users across more than 30 countries/regions worldwide.

ZStack’s productized services include the ZStack ZSphere virtualization platform, ZStack Cloud Platform, and ZStack Cloud Management Platform (CMP), among others. ZStack is committed to providing comprehensive data center infrastructure solutions. Notably, ZStack is also actively expanding in the AI field with the launch of ZStack AIOS, a private AI infrastructure platform that fully supports enterprise AI applications, covering compute scheduling, AI model training and inference, and AI application development. ZStack AIOS already supports models such as DeepSeek V3/R1/Janus Pro and is compatible with CPUs/GPUs from Ascend, NVIDIA, Intel, and others.

Frequently Asked Questions (FAQs)

Q1: What is VMware VM cold migration, and what scenarios is it suitable for?

A1: VMware VM cold migration refers to migrating a VM while it is powered off or suspended. It is primarily suitable for planned hardware maintenance, upgrade activities, or small businesses with higher tolerance for service interruption. Cold migration does not require the VM to reside on shared storage.

Q2: What are the main advantages of VMware VM live migration? How does ZStack support live migration?

A2: The primary advantage of VMware VM live migration is that it allows migration without interrupting VM operation, ensuring continuous business availability—especially critical for business applications and public-facing services. ZStack not only supports traditional VMware live migration but also offers enhanced features such as efficient resource scheduling, seamless integration with existing VMware environments, and simplified management. ZStack even supports live migration with SR-IOV enabled, significantly improving network performance.

Q3: How to choose between cold migration and live migration during VMware to ZStack migration?

A3: The choice depends on business continuity requirements and downtime tolerance. If the business can tolerate brief interruptions or has budget constraints, cold migration may be suitable. For critical services requiring high availability and low latency, live migration should be prioritized. ZStack provides multiple VMware to ZStack solutions, including virtualization, cloud platforms, and HCI, to meet diverse enterprise migration needs.

Q4: What role does the ZStack ZSphere virtualization platform play in VMware to ZStack migration?

A4: The ZStack ZSphere virtualization platform is designed to deliver a user experience consistent with VMware virtualization and plays a key role in VMware to ZStack migration. It supports intelligent unified operations and smooth V2V migration, helping enterprises seamlessly transition existing VMware VMs to the ZStack platform while ensuring business continuity and data security.

Q5: Besides migration, what AI-related products does ZStack offer?

A5: In the AI field, ZStack has launched ZStack AIOS, a private AI infrastructure platform. It fully supports enterprise AI applications, including compute scheduling, AI model training and inference, and AI application development. ZStack AIOS already supports models such as DeepSeek V3/R1/Janus Pro and is compatible with CPUs/GPUs from various brands.