Compaq HSZ80 manual Choosing a Storageset Type, A Comparison of Different Kinds of Storagesets

3–8Creating Storagesets

Choosing a Storageset Type

Different applications may have different storage requirements, so you will probably want to configure more than one kind of storageset in your subsystem.

All of the storagesets described in this book implement RAID technology. Consequently, they all share one important feature: each storageset, whether it contains two disk drives or ten, looks like one large, virtual disk drive to the host.

Table 3–2compares different kinds of storagesets to help you determine which ones satisfy your requirements.

Table 3–2 A Comparison of Different Kinds of Storagesets

Storageset Type	Relative	Request Rate	Transfer Rate (Read/	Applications
	Availability	(Read/Write) I/O per	Write) MB per
		second	second
Array of disk	Equivalent to a	Identical to single	Identical to single
drives (JBOD)	single disk drive	disk drive	disk drive
Stripeset	Proportionate to	Excellent if used	Excellent if used	High performance for
(RAID 0)	number of disk	with large chunk	with small chunk	noncritical data
	drives; worse than	size	size
	single disk drive
Mirrorset	Excellent	Good/Fair	Good/Fair	System drives; critical
(RAID1)				files
RAIDset	Excellent	Excellent/Fair	Good/Poor	High request rates,
(RAID 3/5)				read-intensive, data
				lookup
Striped Mirrorset	Excellent	Excellent if used	Excellent if used	Any critical response-
(RAID 0+1)		with large chunk	with small chunk	time application
		size	size

For a comprehensive discussion of RAID, refer to The RAIDBOOK—A Source Book

for Disk Array Technology.