Xenopsd overview

Xenopsd is the xapi-project VM manager. Xenopsd is responsible for

• starting, stopping, suspending, resuming, migrating VMs
• hotplugging and unplugging disks (VBDs)
• hotplugging and unplugging nics (VIFs)
• hotplugging and unplugging PCI devices
• setting up VM consoles
• running bootloaders
• setting QoS parameters
• configuring SMBIOS tables
• handling crashes
• etc

Check out the full features list.

Principles

1. do no harm: Xenopsd should never touch domains/VMs which it hasn’t been asked to manage. This means that it can co-exist with other VM managers such as ‘xl’ and ‘libvirt’
2. be independent: Xenopsd should be able to work in isolation. In particular the loss of some other component (e.g. the network) should not by itself prevent VMs being managed locally (including shutdown and reboot).
3. asynchronous by default: Xenopsd exposes task monitoring and offers cancellation for all operations. Xenopsd ensures that the system is always in a manageable state after an operation has been cancelled.
4. avoid state duplication: where another component owns some state, Xenopsd will always defer to it. We will avoid creating out-of-sync caches of this state.
5. be debuggable: Xenopsd will expose diagnostic APIs and tools to allow its internal state to be inspected and modified.