Chapter 5

1:	List four types of connecting technologies used in storage subsystems.
A1:	Answer: DASbus, Fibre Channel loop, system I/O bus, and switched connections
2:	Name two types of device redundancy.
A2:	Answer: Mirroring and parity RAID
3:	True or false: Disk drives can have only a single connecting port.
A3:	Answer: False. Fibre Channel drives are dual-ported and SATA, and SAS drives are expected to implement dual porting also.
4:	How is battery backup used in a subsystem?
A4:	Answer: It keeps power to volatile cache memory.
5:	True or false: Temperature is never a problem for disk subsystems.
A5:	Answer: False. Temperature should always be monitored.
6:	What form of device redundancy does not increase capacity?
A6:	Answer: Mirroring is a form of device redundancy that does not increase capacity.
7:	Name two ways in which performance can be boosted in disk subsystems.
A7:	Answer: Parallelism (overlapped I/Os) and caching
8:	What is the difference between hot swapping and hot sparing?
A8:	Answer: Hot swapping allows devices to be removed and inserted into a system without turning off the system. Hot sparing keeps a spare device available to be inserted in subsystem operations without having to remove and replace a device.
9:	Explain the difference between a subsystem and an array.
A9:	Answer: An array is a logical construct, and a subsystem is a physical collection of different components.
10:	True or false: LUN masking blocks I/Os.
A10:	Answer: False. It hides devices by not responding to initiator inquiries.