Emerson ATCA-S201 Software RAID levels and capabilities, Description Data Layout Diagram Level

RTM-ATCA-SXXX Overview

5.3.3Software RAID levels and capabilities

RAID		Description		Data Layout Diagram
Level
RAID4		Three or more disks are grouped in fashion where			Data
		all written data is available even when any single
					S0
		disk drive is removed or fails. RAID4 employs			S1
					S2
		block level striping with a dedicated parity disk.
					S3
					S4
					RAID4
			Stripe	S0	S1	Parity
			Stripe	S2	S3	Parity
			Stripe	S4	S4	Parity
				Disk 1	Disk 2	Disk 3
RAID5	Three or more disks are grouped in fashion where
	all written data is available even when any single				Data
	disk drive is removed or fails. RAID5 employs block				S0
					S1
	level striping with a distributed parity disk.
					S2
	This provides a significant advantage for RAID5 vs				S3
	RAID4 for write operations, because the bandwidth				S4
	of all disks is available for parity write operations.				RAID5
			Stripe	S0	S1	Parity
			Stripe	S2	Parity	S3
			Stripe	Parity	S4	S5
				Disk 1	Disk 2	Disk 3
RAID6	Four or more disks are grouped in fashion where all
	written data is available even when any two disk				Data
	drives are removed or fail. RAID6 employs block				S0
					S1
	level striping with two distributed parity disks.
					S2
	While RAID6 provides a significant redundancy				S3
	advantage, each write spawns two additional parity				S4
	calculations, which in turn adds commensurate				RAID6
	loads on both the internal CPU and memory
	systems.
			Stripe	S0	S1	Parity-P	Parity-Q
			Stripe	S2	Parity-P	Parity-Q	S3
			Stripe
				Parity-P	Parity-Q	S4	S5
			Stripe
				Parity-Q	S6	S7	Parity-P
				Disk 1	Disk 2	Disk 3	Disk 4

6806800H62B ATCA‐S201 Installation and Use Guide 66