HP Storage Management Utility user guide (383075-002, July 2008)

that was originally on the failed drive to the online spare. The system is quickly restored to full RAID-level

data protection. (In the unlikely event that another drive in the array fails while data is being rewritten to

the spare, the logical drive will still fail.)

A spare is assigned to an array and is automatically assigned to all logical drives in the same array.

You do not need to assign a separate spare to each array; you can conﬁgure one hard drive to be

the spare for several arrays.

RAID 0—no fau

lt tolerance

This conﬁguration (Figure 17) provides no protection against data loss when a drive fails. However, it is

useful for rapid storage of large amounts of non-critical data (for printing or image editing, for example),

or when cost is the most important consideration.

Table 3 RAID 0

features

Advantages Disadvantages

Highest performance method for writes.

Alldataonthelogicaldriveislostifaphysicaldrive

fails.

Lowest cost per unit of stored data.

Cannot use a spare.

All drive capacity is used to store data (none needed

for fault tolerance).

Can only preserve data by backing it up to external

storage media.

RAID 1+0—drive mirroring

In this conﬁguration, data on a physical hard drive is duplicated to a second hard drive.

NOTE:

When only two hard drives are included in the array, this fault-tolerance method is called RAID 1. When

more than two hard drives are included in the array, this fault-tolerance method is called RAID 1+0.

(RAID_1 is not supported on the MSA1510i storage system.)

D1 D2

15314

Figure 19 RAID 1 array, with two physical hard drives (D1, D2)

When the array has more than two physical drives, drives are mirrored in pairs (Figure 20).

HP Storage Management Utility user guide