Chapter 8

1:	Why is data redundancy important?
A1:	Answer: It provides protection from data loss.
2:	What are three different forms of redundancy?
A2:	Answer: Duplicate, parity, and delta (difference)
3:	What's the first step in using delta redundancy?
A3:	Answer: Make a complete copy of the data.
4:	List four locations in the I/O path that could contain mirroring operators.
A4:	Answer: Host software, HBAs, network systems, and subsystem controllers
5:	Why can't two targets in a mirrored pair have different sizes (capacities)?
A5:	Answer: File systems are designed to manage a single address space. This means that all storing (block) operations are duplicated within the boundaries of that address space.
6:	How can mirroring improve system performance?
A6:	Answer: Reads can be overlapped, providing parallelism.
7:	Explain how a mirrored pair in a subsystem can be accessed through two different target addresses in a SAN.
A7:	Answer: A single logical unit formed by a mirrored pair can be exported by the subsystem through different port/LUNpairs.
8:	Mirroring is sometimes used for remote data protection up to what distance?
A8:	Answer: 10 miles
9:	If there are three layers of mirrors working in an I/O path, how many copies of data will be created?
A9:	Answer: Eight