Live Migration

Live migration is a technique for moving a virtual machine between physical host servers without requiring a reboot. However, it is not supported equally well by all of the supported OS distributions.

Operating Systems Known not to be Live-Migration Capable Under Xen

Neither NetBSD nor OpenBSD can be live-migrated under Xen. If you are running either of those, we will need to reboot your service to move it to a new host.

Versions of the Linux Kernel That Cannot Be Safely Live-migrated

A commit first appearing in version 4.11 of the Linux kernel broke Xen guest time handling across migration. Migrating a guest running an affected version of the Linux kernel could result in stalled network connections, an unresponsive VPS, inability to properly shut down the VPS, or incorrect timestamps in dmesg output. The only one of those symptoms that is guaranteed is incorrect timestamps in dmesg output, but the rest have been observed.

This issue was fixed in version 5.0.0 of the Linux kernel, and the fix was backported to older kernel series that were still under support. The following series received a backport:

If your VPS is running a kernel with a version number greater or equal to 4.11.0 and less than 5.0.0 and the kernel didn’t receive the backport mentioned above, you’ll need to upgrade your kernel in order for us to be able to safely live-migrate your VPS. See below for a breakdown of upgrade paths for supported distributions. To check your kernel version, use the uname command:

$ uname -r

Known Kernel Upgrade Paths

If your kernel cannot be upgraded, or your operating system is otherwise incapable of being live-migrated, there are options to disable or enable live migration under the Maintenance Options submenu of the VPS console.