The Logical Domains Manager is used to create and manage logical domains, as well as to map logical domains to physical resources. Only one Logical Domains Manager can run on a server.
All logical domains are the same and can be distinguished from one another based on the roles that you specify for them. Logical domains can perform the following roles:
Control domain. The Logical Domains Manager runs in this domain, which 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 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. You can have more than one service domain, and any domain can be configured as a service domain.
I/O domain. An I/O domain has direct access to a physical I/O device, such as a network card in a PCI EXPRESS (PCIe) controller. An I/O domain can own the following:
A PCIe root complex.
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.
A PCIe SR-IOV virtual function. See Creating an I/O Domain by Using PCIe SR-IOV Virtual Functions.
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 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 an eight-socket Oracle SPARC T5-8 server, you can have up to 16 root domains.
The default root domain is the primary domain. You can use non-primary domains to act as 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 but only has virtual I/O devices, such as virtual disks and virtual network interfaces.
You can install the Logical Domains Manager on an existing system that is not already configured with Oracle VM Server for SPARC. In this case, the current instance of the OS becomes the control domain. Also, the system is configured with only one domain, the control domain. After configuring the control domain, you can balance the load of applications across other domains to make the most efficient use of the entire system by adding domains and moving those applications from the control domain to the new domains.
The Logical Domains Manager uses a command-line interface (CLI) to create and configure logical domains. The CLI is a single command, ldm, that has multiple subcommands. See the ldm(1M) man page.
The Logical Domains Manager daemon, ldmd, must be running to use the Logical Domains Manager CLI.
In an Oracle VM Server for SPARC environment, you can configure up to 128 domains on a system (up to 256 on 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.
Oracle VM Server for SPARC uses the virtual network device and virtual network switch device to implement virtual networking. The virtual network (vnet) device emulates an Ethernet device and communicates with other vnet devices in the system by using a point-to-point channel. The virtual switch (vsw) device primarily functions as a multiplexor of all the virtual network's incoming and outgoing packets. The vsw device interfaces directly with a physical network adapter on a service domain, and sends and receives packets on behalf of a virtual network. The vsw device also functions as a simple layer-2 switch and switches packets between the vnet devices connected to it within the system.
The virtual storage infrastructure uses a client-server model to enable logical domains to access block-level storage that is not directly assigned to them. The model uses the following components:
Virtual disk client (vdc), which exports a block device interface
Virtual disk service (vds), which processes disk requests on behalf of the virtual disk client and submits them to the back-end storage that resides on the service domain
Although the virtual disks appear as regular disks on the client domain, most disk operations are forwarded to the virtual disk service and processed on the service domain.
In an Oracle VM Server for SPARC environment, console I/O from the primary domain is directed to the service processor. The console I/O from all other domains is redirected to the service domain that is running the virtual console concentrator (vcc). The domain that runs the vcc is typically the primary domain. The virtual console concentrator service functions as a concentrator for console traffic for all domains, and interfaces with the virtual network terminal server daemon (vntsd) to provide access to each console through a UNIX socket.
A system that runs the Oracle VM Server for SPARC software can configure resources such as virtual CPUs, virtual I/O devices, cryptographic units, and memory. Some resources can be configured dynamically on a running domain, while others must be configured on a stopped domain. If a resource cannot be dynamically configured on the control domain, you must first initiate a delayed reconfiguration. The delayed reconfiguration postpones the configuration activities until after the control domain has been rebooted. For more information, see Resource Reconfiguration.
You can use the ldm command to store the current configuration of a logical domain on the service processor. You can add a configuration, specify a configuration to be used, remove a configuration, and list the configurations. For details, see the ldm(1M) man page. You can also specify a configuration to boot from the SP, as described in Using Oracle VM Server for SPARC With the Service Processor.
For information about managing configurations, see Managing Domain Configurations.