Understanding Multitenancy

Understanding multitenant objects and their relationship is important when setting up and using Photon Controller.

Tenants

Photon Controller is a multi-user system that abstracts physical resources and allocates them across the platform on behalf of users.

The tenant is allocated a pool of resources that can be consumed by users of this tenant. This pool is created through a quota. The process of provisioning resources to users is as follows:

• Create tenant
• Create quotas with a fixed amount of CPU and RAM
• Create projects that allocate resources from the pool of tenant resources

A tenant can have many projects.

Projects

A project is a way to allocate the pool of resources assigned to a tenant through quotas.

Tenant administrators create projects based on a quota and can impose project-specific limits on the project. A project can be granted the right to use all or part of a quota.

Project users can create VMs and disks by paring images with flavors.

Quota

A quota is the mechanism for allocated specific pools of resource (for example, CPU and RAM) to tenants and projects.

Tenants and Resources

A tenant is a unit of administrative control. A system administrator creates tenants and tenant administrators, and uses quotas to limit consumption of resources:

• VMs
• VM memory
• VM CPU capacity

Limits for each class of resource are defined as a tuple that includes a key, a value and a unit.

Key	Value (type)	Unit	Description
vm	integer	COUNT	The number of Virtual Machines that can be created by all projects using this quota
vm.memory	integer	GB	The amount of virtual memory, in gigabytes, that can be consumed by all virtual machines in all projects using this quota
vm.cpu	integer	COUNT	The number of virtual CPU cores that can be consumed by all virtual machines in all projects using this quota

A quota is scoped to a singe tenant, persists for the life of the tenant, and is removed when the tenant is deleted.