You can upgrade VMware ESXi without affecting uptime by using vMotion technology and maintenance mode in a clustered environment. This approach involves live-migrating virtual machines to other hosts before upgrading, then performing a rolling upgrade across your cluster. The key is having multiple ESXi hosts configured with shared storage and proper licensing to enable seamless virtual machine migration during the upgrade process.
Understanding VMware ESXi upgrades and uptime requirements
VMware ESXi upgrade scenarios vary depending on your infrastructure setup and business requirements. In production environments, maintaining continuous service availability is paramount, as even brief downtime can result in significant business disruption and revenue loss.
Several upgrade methods can minimise or eliminate downtime entirely. The most effective approach involves using clustered environments with multiple ESXi hosts, shared storage, and VMware's live migration technologies. This setup allows you to upgrade individual hosts whilst virtual machines continue running on other cluster members.
Single-host environments present greater challenges for zero-downtime upgrades. However, you can still minimise service interruption through careful planning, snapshot management, and scheduling upgrades during low-usage periods.
What is the difference between ESXi updates and upgrades?
ESXi updates are minor patches that address security vulnerabilities, bug fixes, and small feature enhancements within the same major version. These typically require minimal downtime and can often be applied with quick reboots during maintenance windows.
Major upgrades involve moving between different ESXi versions, such as from 7.0 to 8.0. These changes introduce new features, hardware support, and architectural improvements but require more extensive planning and longer maintenance windows.
VMware patching through updates generally has lower risk and shorter downtime requirements. You can often apply these using VMware Update Manager with automated scheduling. Major upgrades need thorough compatibility testing, backup verification, and potentially longer system unavailability periods.
How does vMotion help during ESXi upgrades?
VMware vMotion enables live migration of running virtual machines between ESXi hosts without service interruption. This technology transfers the active memory state, CPU execution context, and network connections seamlessly from one host to another.
During upgrades, vMotion allows you to evacuate all virtual machines from a host before placing it into maintenance mode. The virtual machine migration process typically takes only seconds to minutes, depending on memory usage and network bandwidth.
For zero-downtime upgrades, vMotion requires shared storage accessible by all cluster hosts, compatible CPU architectures, and sufficient network bandwidth. Enhanced vMotion Compatibility mode can help bridge minor CPU differences between hosts, expanding your migration options during upgrade procedures.
What is maintenance mode and when should you use it?
ESXi maintenance mode is a special operational state that prevents new virtual machines from starting on a host whilst allowing safe hardware or software maintenance. When you enable maintenance mode, the system automatically migrates running VMs to other cluster members using vMotion.
You should use ESXi maintenance mode before applying major upgrades, installing hardware, or performing system-level maintenance. The process involves coordinating with Distributed Resource Scheduler (DRS) to ensure proper workload distribution across remaining cluster hosts.
Entering maintenance mode requires cluster configuration with adequate resources on other hosts to accommodate migrated workloads. The system will prevent maintenance mode activation if insufficient resources are available, protecting against service disruption.
How do you perform a rolling upgrade in a vSphere cluster?
A rolling upgrade involves systematically upgrading each ESXi host in sequence whilst maintaining cluster operations. This method ensures continuous service availability throughout the entire ESXi cluster upgrade process.
Start by backing up your vCenter configuration and creating VM snapshots for critical systems. Verify that your cluster has sufficient resources to operate with reduced capacity during individual host upgrades. Update VMware Tools and hardware compatibility on virtual machines before beginning host upgrades.
The upgrade sequence involves:
- Place the first host into maintenance mode
- Allow vMotion to migrate all VMs to other hosts
- Perform the ESXi upgrade on the evacuated host
- Exit maintenance mode and verify proper cluster integration
- Repeat the process for each remaining host
Monitor cluster health between each host upgrade to ensure proper resource distribution and performance levels.
Key takeaways for successful ESXi upgrades
Successful hypervisor upgrade planning requires thorough preparation, proper infrastructure design, and careful execution. Always maintain current backups and test your upgrade procedures in non-production environments before implementing changes.
Clustered environments with shared storage provide the most flexibility for zero-downtime upgrades. Ensure adequate licensing for vMotion functionality and sufficient cluster resources to handle temporary capacity reductions during rolling upgrades.
Consider using ESXi Update Manager for streamlined patch management and automated scheduling. This tool simplifies the upgrade process and provides better visibility into compliance status across your infrastructure.
At Falconcloud, we understand the critical importance of maintaining service availability during infrastructure upgrades. Our managed VMware Cloud services include expert planning and execution of ESXi upgrades, ensuring your business operations continue uninterrupted whilst your infrastructure stays current and secure.