Glossary

AP

See Alternate Pathing.

ap_id

Attachment point identifier; an ap_id specifies the type and location of the attachment point in the system and is unambiguous. There are two types of identifiers: physical and logical. A physical identifier contains a fully specified pathname, while a logical identifier contains a shorthand notation.

Alternate Pathing

Alternate Pathing (AP) is software package which allows the use of multiple paths (connections) between a server and a disk array) or a network. If one path fails, AP can ensure that the disk array or network is still available through the alternate path. For example, the alternate path can be a second port on an interface board, or an entirely separate interface board. See also Dynamic Reconfiguration.

Attachment point

A collective term for a board and its card cage slot. A physical attachment point describes the software driver and location of the card cage slot. A logical attachment point is an abbreviated name created by the system to refer to the physical attachment point.

cfgadm command

The configuration administration command has these options:

-l --display (or list) status -t --initiate testing -c --invoke changes to configuration -x --invoke hardware-specific functions that do not change states -v --verbose

Commands for DR

The common commands include: cfgadm. Refer to the man pages for information about the use of this command. Refer to the release notes for any late-breaking news of other commands.

Condition

The operational status of an attachment point.

Configuration (system)

The collection of attached devices known to the system. The system cannot use a physical device until the configuration is updated. For a DR board, the operating system assigns functional roles to a board and loads device drivers for the board and for devices attached to the board.

Configuration (board)

The operating system assigns functional roles to a board and loads device drivers for the board and for devices attached to the board.

Connection

A board is present in a slot and is electrically connected. The temperature of the slot is monitored by the system.

Detachability

The device Driver supports DDI_DETACH and the device (such as an I/O board or a SCSI chain) is physically arranged so that it can be detached.

Disconnection

The system stops monitoring the board and power to the slot is turned off. A board can be unplugged at any time.

DR

See Dynamic Reconfiguration

Dynamic Reconfiguration

Dynamic Reconfiguration (DR) is software which allows the administrator to (1) view a system configuration, (2) suspend or restart operations involving a port, storage device, or board, and (3) reconfigure the system (detach or attach hot-swappable devices such as disk drives or interface boards) without the need to power down the system. When DR is used with Alternate Pathing or Solstice DiskSuite software (and redundant hardware), the server can continue to communicate with disk drives and networks without interruption while a service provider replaces an existing device or installs a new device. DR supports replacement of a CPU/Memory, provided the memory on the board is not interleaved with memory on other boards in the system.

Hot-plug

Hot-plug boards and modules have special connectors which supply electrical power to the board or module before the data pins make contact. Boards and devices which do not have hot-plug connectors cannot be inserted or removed while the system is running.

Hot Swap

A hot swap device has special DC power connectors and logic circuitry that allow the device to be inserted without the necessity of turning off the system.

Logical DR

A DR operation in which hardware is not physically added or removed. An example is the deactivation of a failed board which is then left in the slot (to avoid changing the flow of cooling air) until a replacement is available.

Physical DR

A DR operation that involves the physical addition or removal of a board. See also "Logical DR" above.

Quiescence

During a DR unconfigure/disconnect operation on a system board with non-pageable Open Boot PROM (OBP) or kernel memory, the operating system is briefly paused, which is known as operating system quiescence. All operating system and device activity on the backplane must cease for a few seconds during a critical phase of the operation.

Receptacle

A receiver such as a board slot or SCSI chain.

State

The operational status of either a receptacle (slot) or an occupant (board).

Suspendability

To be suitable for DR, a device driver must have the ability to stop user threads, execute the DDI_SUSPEND call, stop the clock, and stop the CPUs.

Suspend-safe

A suspend-safe device is one that does not access memory or interrupt the system while the operating system is in quiescence. A driver is considered suspend-safe if it supports operating system quiescence (suspend/resume). It also guarantees that when a suspend request is successfully completed, the device that the driver manages will not attempt to access memory, even if the device is open when the suspend request is made.

Suspend-unsafe

A suspend-unsafe device is one that allows a memory access or a system interruption while the operating system is in quiescence.

Occupant

Hardware resource such as a system board or a disk drive that occupies a DR receptacle or slot.

Unconfiguration

The system detaches a board logically from the operating system and takes the associated device drivers off-line. Environmental monitoring continues, but any devices on the board are not available for system use.