We’re frequently upgrading our systems with most of the changes applied to virtual servers transparently. When changes happen, your virtual server would experience a brief pause of up to 3 seconds. In limited cases, such as specialized hardware, a virtual server might need to be migrated to a different host. If a migration is required, the virtual server is shut down, migrated, then restarted. A virtual server might be migrated in the following cases:
A host needs to be updated, is being decommissioned or is not allowed to take on new instances. If a host is marked for any of these changes when one of its virtual servers is restarted from the IBM Cloud console, the restart automatically triggers the virtual server to be migrated to a different host.
Infrastructure maintenance. An email is sent that indicates maintenance is required on a system that is hosting your virtual server. The email contains instructions on how to initiate the migration during the maintenance period. Alternatively, the virtual server automatically migrates to complete the required maintenance.
An upgrade of an existing instance is deployed. For consistent performance, if you upgrade an instance it might be migrated to a different host to ensure that it receives the appropriate dedicated CPU and memory.
A dedicated host fails. When a dedicated host fails, dedicated instances are migrated to another empty host without using any existing capacity that you might have.
A virtual host fails. When a virtual host fails, your instances are migrated to another host within the environment. When a host failure occurs, we automatically detect this failure and move your instance onto a new host. Failure detection typically occurs within 1 minute; your virtual server is rescheduled to a new host within 5 minutes; and the server is up and running within 7 minutes. To opt out of auto-recovery, a support case must be opened with the request.
During a maintenance window, you might see a Migrate Host option display in the Actions menu of your device in the IBM Cloud console. Migrate Host allows you to migrate the virtual server to a new host at your convenience during a specified maintenance period. If you don’t initiate the migration during the maintenance period, then the virtual server is automatically migrated to complete the required maintenance. The Migrate Host option doesn’t persist and is available only during maintenance periods that are communicated through maintenance notifications.
You might also see the Migrate Host option if one of your virtual servers is required to have a certain level of hypervisor that isn’t available on the current host. \r