HP Array Controller HSG V8.7 Software - Manual (Page 90)

3–12 HSG80 User’s Guide
n Applications that make requests for small amounts of
sequentially-located data
n Applications that make synchronous random requests for small
amounts of data
By spreading the traffic evenly across the buses, you will ensure that no
bus handles the majority of data to the storageset.
Using Mirrorsets to Ensure Availability
Mirrorsets use redundancy to ensure availability, as illustrated in Figure
3–5. For each primary disk drive, there is at least one mirror disk drive.
Thus, if a primary disk drive fails, its mirror drive immediately provides
an exact copy of the data.
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:
n A controller can support up to 30 storagesets, consisting of
mirrorsets and RAIDsets. Mirrorsets that are members of a stripeset
count against this limitation (refer to Table 3–1).
n 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.
Disk 10100
Disk 20100
Disk 30100
Disk 10000
Disk 20000
Disk 30000
CXO5511A
A' A
B' B
C' C
Mirror drives contain
copy of data