1/11/2024 0 Comments Instal Starus Photo Recovery 6.6(The sole difference would be the SERVER_ID field in /etc/one/nf.)Ī working database connection of the same type. The same software configuration of the servers. (Recommended) identical server capacities. You can add, replace or remove servers once the cluster is up and running.Īn odd number of servers (three is recommended). The recommended deployment size is either three or five servers, which provides a fault-tolerance for one or two server failures, respectively. This means that reads can be arbitrarily stale but generally within the round-trip time of the network. In OpenNebula, read-only operations can be performed through any oned server in the cluster and write operations issued to the follower nodes are forwarded to the leader node. The latency of DB operations is thus increased, but the system state is safely replicated and the cluster can continue its operation in case of node failure. a new VM is added to the system), the leader updates the log and replicates the entry in a majority of followers before actually writing it to the database. If a leader fails to send the heartbeat, followers are promoted to candidates and start a new election. The leader periodically sends heartbeats to the other servers, the followers, to keep its leadership. The servers in the OpenNebula cluster elect a single node to be the leader. To preserve a consistent view of the system across servers, modifications to the system state are performed through a special node, the leader. Log - sequence of SQL statements that are consistently applied to the OpenNebula DB in all servers to evolve the system state. System State - OpenNebula data stored in the database tables (users, ACLs, or the VMs in the system). These details are provided for those who wish to learn about them to fine-tune their deployments.Ī consensus algorithm is built around two concepts: You do not need to know these details to effectively operate OpenNebula on HA. This section covers some internals on how OpenNebula implements Raft. If you are interested in fail-over protection against hardware and operating system outages within your virtualized IT environment, check the Virtual Machines High Availability Guide.
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