Compaq HSZ80 manual Considerations for Planning a Mirrorset

3–13

	k 10	10
is
D		0
	A
	k 20
is		10
D		0
	B
	k 30	10
is
D		0

C

	k 10
is		00
D			0
		A'
isk 2000
D			0
		B'
	k 30
is		00
D			0

C'

Mirror drives contain copy of data

CXO5511A

Figure 3–5. Mirrorsets Maintain Two Copies of the Same Data

Considerations for Planning a Mirrorset

Keep these points in mind as you plan your mirrorsets:

■A controller can support up to 30 storagesets, consisting of mirrorsets and RAIDsets. Mirrorsets that are members of a stripeset count against this limitation (see Table 3–1).

■Data availability with a mirrorset is excellent but costly—you need twice as many disk drives to satisfy a given capacity requirement. If availability is your top priority, consider using redundant power supplies and dual-redundant controllers.

■You can configure up to 30 mirrorsets per controller or pair of dual-redundant controllers. Each mirrorset contains a minimum of one member and a maximum of six members.

■A write-back cache module is required for mirrorsets, but write-back cache need not be enabled for the mirrorset to function properly.

■Both write-back cache modules must be the same size.

Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide