Managing High Availability Clusters

This chapter explains managing High Availability for servers that participate in Parallels Cloud Storage clusters.

High Availability keeps virtual machines, Containers, and iSCSI targets operational even if the Hardware Node they are hosted on fails. In such cases, the affected virtual environments continue working on other, healthy Hardware Nodes in the cluster. High Availability is ensured by:

• Replication of metadata servers. For a Parallels Cloud Storage cluster to function, not all but just the majority of MDS servers must be up. By setting up multiple MDS servers in the cluster you will make sure that if an MDS server fails, other MDS servers will continue controlling the cluster.
• Replication of data. All data chunks are replicated and the replicas are kept on different chunk servers. If a chunk server fails, other chunk servers will continue providing the data chunks that were stored on the failed server.
• Monitoring of Hardware Nodes' health.