System Administration Guide: Virtualization Using the Solaris Operating System

About Domains

The control domain and the guest domain are separate entities.

Each domain has a name and a UUID. Domains can be renamed, but typically retain the same UUID.

A domain ID is an integer that is specific to a running instance. This ID changes whenever a guest domain is booted. A domain must be running to have a domain ID. UUID 0 is assigned to dom0.

Control Domain 0

For the latest information on Domain 0, see the document dom0 configuration for admins .

The control domain is a version of Solaris modified to run under the xVM hypervisor. When the control domain is running, the control tools are enabled. In most other respects, the control domain 0 instance runs and behaves like an unmodified instance of the Solaris Operating System.

The control domain provides console access to the guest domains it controls, but you cannot otherwise access a guest domain from the control domain unless you use the remote login commands rlogin, telnet, and ssh. A control domain should be reserved for system management work associated with running a hypervisor. This means, for example, that users should not have logins on the control domain. The control domain provides shared access to a physical network interface to the guest domains, which have no direct access to physical devices.

If a control domain crashes with a standard Solaris panic, the dump will include just the control domain. Also see About Crash Dumps.

The following information applies to the control domain:

Guest Domain Space Requirements

Size your domain as you would configure a machine to do the same workload.

The virtual disk requirement is dependent on the guest operating system and software that you install.

Domain States

A domain can be in one of six states. States are shown in virsh list displays.

For example:

#  virsh list
ID    Name        State  
0     Domain-0    running
2     sxc18       paused

The states are:

r, running

The domain is currently running on a CPU.

b, blocked

The domain is blocked, and not running or able to be run. This can be caused because the domain is waiting on IO (a traditional wait state) or it has gone to sleep because there was nothing running in it.

p, paused

The domain has been paused, usually through the administrator running virsh suspend. When in a paused state, the domain still consumes allocated resources like memory, but is not eligible for scheduling by the hypervisor. Run resume domain to place the domain in the running state.

s, in shutdown

The domain is in process of shutting down, but has not completely shutdown or crashed.

s, shutoff

The domain is shut down.

c, crashed

The domain has crashed. Usually this state can only occur if the domain has been configured not to restart on crash. See xmdomain.cfg(5) for more information.