Galaxy Metal Gear 65 manual Comparing RAID Levels

Galaxy 65 User Guide

A.2 Comparing RAID Levels

Table 1–2illustrates the differences between the different RAID levels.

Table 1–2	Comparing RAID levels
RAID Level	Min No. of
	Drives	Description	Strengths	Weaknesses
RAID 0	2	Data striping without	Highest performance	No data protection—one drive
		redundancy		fails, all data is lost
RAID 1	2	Disk mirroring	Very high:	High redundancy cost
				overhead—because all data is
			Performance	duplicated, twice the storage
			Data protection	capacity is required
			Minimal penalty on write
			performance
RAID 2	N/A	No practical use	Previously used for RAM	No practical use—same
			error environments	performance can be achieved by
			correction (known as	RAID 3 at lower cost
			Hamming Code) and in disk
			drives before the use of
			embedded error correction
RAID 3	3	Block-level data striping	Excellent performance for	Not well-suited for transaction-
		with dedicated parity	large, sequential data	oriented network applications;
		drive	requests	single parity drive does not
				support multiple, concurrent write
				requests
RAID 4 (Not	3	Block-level data striping	Data striping supports	Write requests suffer from same
widely used)		with dedicated parity	multiple simultaneous read	single parity-drive bottleneck as
		drive	requests	RAID 3; RAID 5 offers equal data
				protection and better
				performance at same cost
RAID 5	3	Block-level data striping	Best cost/performance for	Write performance is slower than
		with distributed parity	transaction-oriented	RAID 0 or RAID 1
			networks; very high
			performance and data
			protection; supports multiple
			simultaneous reads and
			writes; can also be optimized
			for large, sequential
			requests
RAID 50	6	Combination of RAID 0	Better random performance	Lower storage capacity than
		(data striping) and	and data protection than	RAID 5
		RAID 5 with distributed	RAID 5; supports more
		parity	drives than RAID 5

92