HP P3410A - NetRAID 1M RAID Controller Installation And Configuration Manual page 38

Chapter 4
The physical drives in an array can be all on the same channel, or they
can be on separate channels.
You might plan to reserve one or more physical drives for use as a hot
spare. See "Plan Hot Spares (Optional)" later in this chapter for more
information.
When you create your arrays, you should look ahead toward the logical drives
that you will configure later. (Logical drives are discussed in "Plan Logical
Drives" later in this chapter.) Here are some considerations about logical drives
that might impact how you set up your arrays:
Consider what RAID levels you will need.
Different RAID levels require different minimum numbers of physical
drives. For example, RAID 1 requires exactly two physical drives,
RAID level 5 requires at least three physical drives, and arrays with
only one physical drive must be assigned RAID 0.
Different RAID levels reserve different amounts of capacity to provide
redundancy.
A single array can be divided into a maximum of 40 logical drives.
A single HP NetRAID-1M or 2M adapter can control a maximum of 40
logical drives.
If you want to use the online capacity expansion feature later, logical
drives cannot span arrays and there must be only one logical drive per
array.
If you want one logical drive to span two or more arrays:
Spanned arrays must be numbered consecutively.
Spanned arrays must contain the same number of disk drives per
array.
Although each physical drive in an array must have the same capacity,
one logical drive can span two or more arrays of different capacities.
For example, one array might contain three drives of 1 GB each, and
the second array might contain three drives of 5 GB each. One logical
drive can span both of these arrays.
Spanned arrays must be controlled by the same adapter.
As you plan your arrays, it might help to sketch your configuration. Figures 4-2
and 4-3 are examples.
In Figure 4-2, Logical Drive 1 (labeled "LD1") spans arrays A0 and A1,
occupying space in both. Each array of physical drives is on a separate channel.
30
Planning