A cloud category type reservation provides access to the provisioning services of a cloud service account for a particular vRealize Automation business group. Available cloud reservation types include Amazon, OpenStack, vCloud Air, and vCloud Director.
A reservation is a share of the memory, CPU, networking, and storage resources of one compute resource allocated to a particular vRealize Automation business group.
A business group can have multiple reservations on one endpoint or reservations on multiple endpoints.
The allocation model for a reservation depends on the allocation model in the associated datacenter. Available allocation models are Allocation Pool, Pay As You Go, and reservation pool. For information about allocation models, see thevCloud Director or vCloud Air documentation.
In addition to defining the share of fabric resources allocated to the business group, a reservation can define policies, priorities, and quotas that determine machine placement.
To provision successfully, the reservation must have sufficient available storage. The reservation's storage availability depends on:
How much storage is available on the datastore/cluster.
How much of that storage is reserved for that datastore/cluster.
How much of that storage is already allocated in vRealize Automation
For example, even if the vCenter Server has storage available for the datastore/cluster, if sufficient storage is not reserved in the reservation then provisioning fails with a "No reservation is available to allocate..." error. The allocated storage on a reservation depends on the number of VMs (regardless of their state) on that specific reservation. See the VMware Knowledge Base article Machine XXX: No reservation is available to allocate within the group XXX. Total XX GB of storage was requested (2151030) at http://kb.vmware.com/kb/2151030 for more information.