Oracle VM Server for SPARC provides highly efficient, enterprise-class virtualization capabilities for Oracle's SPARC T-Series servers as well as the SPARC M5 server and Fujitsu M10 systems. Using the Oracle VM Server for SPARC software, you can create many virtual servers, called logical domains, on a single system. This kind of configuration enables you to take advantage of the massive thread scale offered by these SPARC servers and the Oracle Solaris OS.
A logical domain is a virtual machine that contains a discrete logical grouping of resources. A logical domain has its own operating system and identity within a single computer system. Each logical domain can be created, destroyed, reconfigured, and rebooted independently, without requiring you to perform a power cycle of the server. You can run a variety of application software in different logical domains and keep them independent for performance and security purposes.
For information about using the Oracle VM Server for SPARC software, see Oracle VM Server for SPARC 3.1 Administration Guide and Oracle VM Server for SPARC 3.1 Reference Manual . For information about the required hardware and software, see Oracle VM Server for SPARC 3.1 Release Notes .
Figure 1 - Hypervisor Supporting Two Logical Domains
The Oracle VM Server for SPARC software uses the following components to provide system virtualization:
Hypervisor. The hypervisor is a small firmware layer that provides a stable virtualized machine architecture to which an operating system can be installed. Oracle's Sun servers that use the hypervisor provide hardware features to support the hypervisor's control over the operating system activities on a logical domain.
The number of domains and the capabilities of each domain that a specific SPARC hypervisor supports are server-dependent features. The hypervisor can allocate subsets of the server's CPU, memory, and I/O resources to a given logical domain. This allocation enables the support of multiple operating systems simultaneously, each within its own logical domain. Resources can be rearranged between separate logical domains with an arbitrary granularity. For example, CPUs are assignable to a logical domain with the granularity of a CPU thread.
The service processor (SP), also known as the system controller (SC), monitors and runs the physical machine. The Logical Domains Manager, and not the SP, manages the logical domains themselves.
Control domain. The Logical Domains Manager runs in this domain and enables you to create and manage other logical domains and to allocate virtual resources to other domains. You can have only one control domain per server. The control domain is the first domain that is created when you install the Oracle VM Server for SPARC software. The control domain is named primary.
Service domain. A service domain provides virtual device services to other domains such as a virtual switch, a virtual console concentrator, and a virtual disk server. Any domain can be configured as a service domain.
I/O domain. An I/O domain has direct access to physical I/O devices such as a network card in a PCI EXPRESS (PCIe) controller. An I/O domain can own a PCIe root complex or it can own a PCIe slot or on-board PCIe device by using the direct I/O (DIO) feature. See Creating an I/O Domain by Assigning PCIe Endpoint Devices in Oracle VM Server for SPARC 3.1 Administration Guide .
An I/O domain can share physical I/O devices with other domains in the form of virtual devices when the I/O domain is also used as a service domain.
Root domain. A root domain has a PCIe root complex assigned to it. This domain owns the PCIe fabric of that root complex and provides all fabric-related services such as fabric error handling. A root domain is also an I/O domain, as it owns and has direct access to physical I/O devices.
The number of root domains that you can have depends on your platform architecture. For example, if you are using a SPARC T4-4 server from Oracle, you can have up to four root domains.
Guest domain. A guest domain is a non-I/O domain that consumes virtual device services that are provided by one or more service domains. A guest domain does not have any physical I/O devices. It has only virtual I/O devices such as virtual disks and virtual network interfaces.
Often, an Oracle VM Server for SPARC system has only a control domain that provides the services that are performed by I/O domains and service domains. To improve redundancy and platform serviceability, consider configuring more than one I/O domain on your Oracle VM Server for SPARC system.