8.2. High Availability for the Services

On top of highly available metadata services and enabled management node HA, Virtuozzo Hybrid Infrastructure provides additional high availability for the following services:

  • Admin panel. If the management node fails or becomes unreachable over the network, an admin panel instance on another node takes over the panel’s service so it remains accessible at the same dedicated IP address. The relocation of the service can take several minutes. Admin panel HA is enabled along with management node HA.
  • Virtual machines. If a compute node fails or becomes unreachable over the network, the virtual machines hosted on it are evacuated to other healthy compute nodes based on their free resources. The compute cluster can survive the failure of only one node. By default, high availability for virtual machines is enabled automatically after creating the compute cluster and can be disabled manually, if required.
  • iSCSI service. If the active path to volumes exported via iSCSI fails (e.g., a storage node with active iSCSI targets fails or becomes unreachable over the network), the active path is rerouted via targets located on healthy nodes. Volumes exported via iSCSI remain accessible as long as there is at least one path to them.
  • S3 service. If an S3 node fails or becomes unreachable over the network, name server and object server components hosted on it are automatically balanced and migrated between other S3 nodes. S3 gateways are not automatically migrated; their high availability is based on DNS records. You need to maintain the DNS records manually when adding or removing S3 gateways. High availability for the S3 service is enabled automatically after enabling the management node HA and creating an S3 cluster from three or more nodes. An S3 cluster of three nodes may lose one node and remain operational.
  • NFS shares. If a storage node fails or becomes unreachable over the network, NFS volumes located on it are migrated between other NFS nodes. High availability for NFS volumes on a storage node is enabled automatically after creating an NFS cluster.
  • Backup gateway service. If a backup gateway node fails or becomes unreachable over the network, other nodes in the backup gateway cluster continue to provide access to the chosen storage backend. Backup gateways are not automatically migrated; their high availability is based on DNS records. You need to maintain the DNS records manually when adding or removing backup gateways. High availability for backup gateway is enabled automatically after creating a backup gateway cluster from two or more nodes (not applicable to external NFS). Access to the storage backend remains until at least one node in the backup gateway cluster is healthy.