Yes, there are a few known limitations or issues related with OpenVZ performance:
1. Shared Kernel: As all VEs share the same kernel, a kernel-level issue can adversely affect all containers leading to potential performance issues.
1. Limited Scalability: OpenVZ offers less scalability compared to other virtualization technologies like KVM or Xen.
1. No Dedicated Resources: Since OpenVZ shares resources among containers rather than dedicating specific resources, one container using excessive resources can impact performance in other containers.
1. Limited OS Choices: Since OpenVZ VEs share the same kernel, users are limited to the host’s OS selection, and running different operating systems across containers is not supported, potentially impacting operational flexibility and performance.
1. Kernel Upgrades and Customization: Customizing or upgrading the kernel inside a container is not possible with OpenVZ. This can limit a user’s ability to apply performance-enhancing tweaks or updates.
1. Disk I/O Performance: Potential ‘I/O noisy neighbor’ issues can arise when one container makes heavy use of disk I/O and impacts performance for other containers.
1. Network Performance: Similar to Disk I/O, one container with high network usage can potentially impact network performance for other containers.
It’s important to remember that these are not bugs or unavoidable issues. Rather, they are fundamental characteristics of how container-based virtualization like OpenVZ works. These issues can be alleviated or mitigated with good management practices and by employing specific configurations.
