Compaq Infortrend manual Any spare drives?, Limitations?, RAID Levels

Table 2 - 1		RAID Levels
RAID Level	Description		Capacity Data Availability
NRAID	Non-RAID		N	N/A
RAID 0	Disk Striping		N	==NRAID
RAID 1 (0+1)	Mirroring Plus Striping (if N>1)		N/2	>>NRAID
				==RAID 5
RAID 3	Striping with Parity on		N-1	>>NRAID
	dedicated disk			==RAID 5
RAID 5	Striping with interspersed		N-1	>>NRAID
	parity			==RAID 5
Logical	Striping one or more logical		*	Higher; depends
Volume	drives of different RAID levels			on its members
RAID Level		Performance Sequential	Performance Random
NRAID		Drive	Drive
RAID 0		R: Highest	R: High
		W: Highest	W: Highest
RAID 1 (0+1)		R: High	R: Medium
		W: Medium	W: Low
RAID 3		R: High	R: Medium
		W: Medium	W: Low
RAID 5		R: High	R: High
		W: Medium	W: Low
Logical Volume		Depends on its members;	Depends on its members
		see above

8. Any spare drives?

(Swap Drive Rebuild / Spare Drive Rebuild)

Spare drives allow for the unattended rebuilding of a failed drive, heightening the degree of fault tolerance. If there is no spare drive, data rebuild has to be manually initiated by replacing a failed drive with a healthy one.

As is often ignored, a spare drive (whether dedicated or global) must have a capacity no smaller than the members of a logical drive.

9. Limitations?

Firmware 3.31 and above support 64-bit LBA. A maximum of 64TB capacity can be included in single logical drive.

Up to 128 members can be included in each logical drive.

Extreme array sizes can cause operational problems with system backup and should be avoided.

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