A host is a single computer. Hosts provide the computing resources that run the guest virtual machines. Each host has hypervisor software installed on it to manage the guest VMs. For example, a Linux KVM-enabled server, a Citrix XenServer server, and an ESXi server are hosts.
The host is the smallest organizational unit within a CloudStack deployment. Hosts are contained within clusters, clusters are contained within pods, and pods are contained within zones.
Hosts in a CloudStack deployment:
Provide the CPU, memory, storage, and networking resources needed to host the virtual machines
Interconnect using a high bandwidth TCP/IP network and connect to the Internet
May reside in multiple data centers across different geographic locations
May have different capacities (different CPU speeds, different amounts of RAM, etc.), although the hosts within a cluster must all be homogeneous
Additional hosts can be added at any time to provide more capacity for guest VMs.
CloudStack automatically detects the amount of CPU and memory resources provided by the Hosts.
Hosts are not visible to the end user. An end user cannot determine which host their guest has been assigned to.
For a host to function in CloudStack, you must do the following:
Install hypervisor software on the host
Assign an IP address to the host
Ensure the host is connected to the CloudStack Management Server
