Virtual Input/Output

In an Oracle VM Server for SPARC environment, you can configure up to 128 domains on a system (up to 256 on a Fujitsu SPARC M12 server and a Fujitsu M10 server). Some servers, particularly single-processor and some dual-processor systems, have a limited number of I/O buses and physical I/O slots. As a result, you might be unable to provide exclusive access to a physical disk and network devices to all domains on these systems. You can assign a PCIe bus or endpoint device to a domain to provide it with access to a physical device. Note that this solution is insufficient to provide all domains with exclusive device access. This limitation on the number of physical I/O devices that can be directly accessed is addressed by implementing a virtualized I/O model. See Configuring I/O Domains.

Any logical domains that have no physical I/O access are configured with virtual I/O devices that communicate with a service domain. The service domain runs a virtual device service to provide access to a physical device or to its functions. In this client-server model, virtual I/O devices either communicate with each other or with a service counterpart through interdomain communication channels called logical domain channels (LDCs). The virtualized I/O functionality includes support for virtual networking, storage, and consoles.