IBM ServeRAID-4 Ultra160 Series, User Reference

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Then, create a spanned array
(labeled as 1) that spans the
three arrays.
A A
B C
111
A
1
A sub-logical drive is created
within each array (A, B, and
C). Then, the data is striped
across the physical drives in
the array, creating blocks.
Notice that, in each array, the
data on the drive on the right
is a copy of the drive on the
left. This is because the
sub-logical drives (A, B, and
C) are RAID level-1 in a RAID
level-10 implementation (see
the following table).
A A
B C
1
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
11
A
1
Then, create a logical drive
within the spanned array (1).
The data is striped across this
logical drive, creating blocks.
Notice that none of these
blocks are redundant. This is
because the logical drive (1)
is RAID level-0 in a RAID
level-x0 implementation (see
the following table).
A A
B
C
1
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
1
2
3
4
5
7
6
8
11
A
1
1
2 3
5
4
7
10
8
11
6
9
12
RAID level Sub-logical drive Spanned array logical drive
00 RAID level-0 RAID level-0
10 RAID level-1 RAID level-0
1E0 RAID level-1E RAID level-0
50 RAID level-5 RAID level-0
With RAID level-10, 1E0, and 50, if one of the physical drives fails in a sub-logical
drive, the ServeRAID controller switches read and write requests to the remaining
functional drives in the sub-logical drive. With RAID level-00, a physical drive failure
within the sub-logical drive results in loss of data.
Chapter 3. Understanding RAID technology
23