High Availability

You can do the following at Virtual Machine Manager > Virtual Machine:

Limitations

Please note the following limitations:

Host Role

The following hosts are required for running High Availability on the virtual machine:

High Availability Status

Below are possible types of High Availability status:

Resource Reservation

In order to ensure successful failover or switchover when errors occur, the system will reserve CPU and memory resources on the active and passive servers when you enable or edit High Availability on the virtual machine. In addition, when the specifications of the virtual machine are modified, required resources will be changed and reserved accordingly. For example, if a host with 4 GB memory is the passive server of a virtual machine with 1 GB memory, the system will reserve 1 GB memory on this passive server to ensure the virtual machine can be successfully run in the event of a switchover/failover. However, if the memory on the host is insufficient, memory reservation may fail, and the system may fail to perform switchover or failover. Likewise, when the rest of the memory is reserved for the virtualization cluster, this passive server will not be able to run any other virtual machines.

Switchover

Switchover refers to an automatic switch from an abnormal yet still functioning active server to a healthy passive server in a virtualization cluster. After performing the switchover, the active server assumes the role of the passive server, and the passive server assumes the role of the active server. The system will initiate a switchover when the active server is under the following situations:

Failover

The system will initiate a failover when the active server is inaccessible or the virtual machine is offline. When performing failover, the virtual machine will be automatically restarted on the passive server, and thus the connections may be temporarily unstable. The system will initiate a failover in the following situations: