Sun Microsystems 5310 NAS manual 1Standard Terms, Nbd

TABLE 4-1Standard Terms

Term	Definition
Master	The system that is being mirrored or the source system
Mirror	The system that is being used to mirror the Master system, or the
	target system
Checkpoint /	A static image of the file system at a fixed point in time
Snapshot
Client	A network computer that initiates a read or write request
Delta	The filesystem blocks that have changed during a fixed period of
	time, usually between successive checkpoints
Disaster Recovery	The act of recovering access to computer systems, networks and
(DR)	data subsequent to a catastrophe, e.g., the loss of a Datacenter
Synchronous	Transaction complete is not reflected back to the client until the
Mirroring	transaction has been committed to both the Master and Mirror
	systems
Asynchronous	Transaction complete is reflected back to the client when the
Mirroring	transaction is committed to the Master system
Mirror	Abstract definition of the system involving a master volume and
	mirror volume, controlled by the mirror service.
Master System	The Sun StorEdge 5310 NAS system on which the source, or live,
	volume is located.
Mirror System	The Sun StorEdge 5310 NAS system on which the target, or
	duplicate, volume is located.
NBD	Network Block Device. A network interface to a remote volume.
	NBD is used as a transport mechanism used by the mirror service.
	NBD is also the partition type for the remote mirror volume.
Quality of Service	For the purposes of this document, a generic term referring to the
(QOS)	quality of service provided to a network user or system over a
	network link. It should not be confused with QoS, which is a
	standard for controlling data/packet flow on an IP network.
Transaction	A confirmation from the storage subsystem to the client that a write
Complete	transaction has been committed to disk.

4-2Sun StorEdge 5310 NAS Troubleshooting Guide • December 2004