Clusters in VMware vCenter Server are an important way to group ESXi hosts. When a host is added to a cluster, the host’s resources become part of the cluster’s resources.
Within a cluster, resource management elements can be defined; for example, a resource pool, reservation, or limit. vCenter Server also provides features like DRS and HA at a cluster level.
The performance of clustering in vCenter Server 6.0 has improved over 5.5 in two key areas:
- Increase in supported single cluster limit: 64 ESXi hosts and 8,000 virtual machines (in 5.5, this was 32 ESXi hosts and 3,000 virtual machine).
- Linear throughput scaling with an increase in cluster size and workload
Other performance highlights include impressive improvements:
- Up to 66% improvement in operational throughput over vCenter Server 5.5
- Improved performance under very heavy workloads
- Performance parity between vCenter Server on Windows and VCSA
- Significantly faster virtual machine operations
Central to this paper is a case study that shows the performance of vCenter Server 6.0 clusters and illustrates the performance improvements over vCenter Server 5.5. This paper also compares the performance of vCenter Server on Windows and the vCenter Server Appliance (VCSA).