Compaq HSZ80 manual GL-18Glossary, Vhdci

GL–18Glossary
VHDCI	Very High Density Cable Interface. A 68-pin interface. Required for
	Ultra SCSI connections.
virtual terminal	A software path from an operator terminal on the host to the controller’s CLI
	interface, sometimes called a host console. The path can be established via
	the host port on the controller (using HSZterm) or via the maintenance port
	on the controller.
VTDPY	Virtual Terminal Display utility.
warm swap	A device replacement method that allows the complete system to remain
	online during device removal or insertion. The system bus may be halted, or
	quiesced, for a brief period of time during the warm-swap procedure.
Worldwide name	A unique 64-bit number assigned to a subsystem by the Institute of Electrical
	and Electronics Engineers (IEEE) and set by Compaq manufacturing prior to
	shipping. This name is referred to as the node ID within the CLI.
write-back caching	A cache management method used to decrease the subsystem’s response
	time to write requests by allowing the controller to declare the write
	operation “complete” as soon as the data reaches its cache memory. The
	controller performs the slower operation of writing the data to the disk drives
	at a later time.
write-through	A cache management method used to decrease the subsystem’s response
caching	time to a read. This method allows the controller to satisfy the request from
	the cache memory rather than from the disk drives.
write hole	The period of time in a RAID level 1 or RAID level 5 write operation when
	an opportunity emerges for undetectable RAIDset data corruption. Write
	holes occur under conditions such as power outages, where the writing of
	multiple members can be abruptly interrupted. A battery backed-up cache
	design eliminates the write hole because data is preserved in cache and
	unsuccessful write operations can be retried.