IBM 866011U - Netfinity 5500 - 8660, Hardware Maintenance Manual

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The Enhanced RAID level 1 stripes data and copies of the
data across all the drives in the array. As with the
standard RAID level 1, the data is mirrored, and the
capacity of the logical drive is 50% of the physical capacity
of the grouping of hard disk drives in the array.
The following illustration shows data arranged in an array
with three hard disk drives. The logical drive is assigned
the Enhanced level 1. Notice that the mirror of the first
data stripe (
XXX YYY ZZZ
) is shifted one drive. The other
data stripes in level 1 follow the same pattern.
Table 1. Enhanced RAID Level 1
If you have only two drives available, the second drive is a
mirror copy of the first drive.
RAID level 5:
RAID level 5 stripes data and parity
across all drives in the array. When an array is assigned
level 5, the capacity of the logical drive is reduced by one
drive (for data parity storage).
RAID level 5 is generally the most desirable choice,
because it offers both data protection and increased
throughput. RAID level 5 gives you higher capacity than
level 1, but level 1 offers better performance.
If you want to have a hot-spare drive (that is, a drive that
can be automatically used to replace a similar drive that
fails) and also assign RAID level 5, you must have at least
four hard disk drives in the server.
ServeRAID menus, screens, and drive
states:
The following information describes the Main
Menu, the ServeRAID screens and pop-up windows, the
physical device states, and the logical drive states.
. . . .
. .
Stripe
XXX YYY ZZZ
Mirrored stripe
ZZZ XXX YYY
Stripe
AAA BBB CCC
Mirrored stripe
CCC AAA BBB
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