Concepts
hv separates physical infrastructure from the teams using it. Understanding that separation helps choose the right page, grant access and diagnose an apparently missing resource. Before assigning roles or moving workloads, identify their Pool, Silo and Project. The result should be clear ownership without unnecessarily broad Fleet access.
Infrastructure and ownership
The Fleet is the infrastructure managed by one hv deployment. A Pool groups Hosts under one xapi coordinator. A Host is a machine running Xen, dom0 and xapi. The coordinator manages the Pool's xapi state; each Host still runs its own hv-agent.
A Silo is a tenant boundary. Every Account, Group and Project belongs to one Silo. A Project owns VMs, disks, Snapshots, Images and VPCs. A Project can use multiple Pools where its Silo has visibility; a Pool is therefore not the same boundary as a Project.
A Personal project belongs to one Account and cannot be shared. A Shared project grants membership to Accounts or Groups in its Silo. Resources imported from outside hv can be Unassigned until a Fleet administrator adopts them into a Project.
VM resources
A VM runs an operating system. A Template is a definition used to create VMs; an Image presents a Template as a boot source. A Snapshot records a VM at a point in time, with disks and optionally memory. It is not an independent backup merely because it appears in a separate list.
An SR, storage repository, holds virtual disk images called VDIs. A VBD attaches a VDI to a VM. A PBD connects a Host to an SR. These distinctions explain why a disk can exist but be unavailable to a particular Host or unattached to a VM.
A Network provides layer-2 connectivity. A PIF connects a Host to a Network; a VIF is a VM's virtual NIC. A VPC is a Project-owned overlay Network spanning a Pool's Hosts. It does not automatically supply addresses, DHCP, NAT or a router.
Access and operations
An Account identifies a person or API client; a Group collects Accounts. Project roles control one Project, Silo roles apply across its Projects, and Fleet roles control infrastructure. A token's scopes restrict its Account's rights. See users and access.
A Task records a long-running operation. A backup Remote stores recovery data; a backup job selects VMs, a Schedule and Retention. A Release repository supplies trusted hv releases, distinct from an SR and from a backup Remote.
Apply the model
Start with Projects for workload ownership and System for Fleet infrastructure. Select the Project before creating a VM, then check the image, SR and Network offered. Review Utilization for quota and provisioning. If an object is absent, check Silo visibility, Project membership and token scopes before assuming it was deleted. A System page returning 404 for an Account without a Fleet role is an intentional access boundary.