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3–16 Creating Storagesets
For example, in a three-member RAIDset that contains disk drives 10000, 20000, and
30000, the first chunk of an I/O request is written to 10000, the second to 20000, then
parity is calculated and written to 30000; the third chunk is written to 30000, the
fourth to 10000, and so on until all of the data is saved.
The relationship between the chunk size and the average request size determines if
striping maximizes the request rate or the data-transfer rate. You can set the chunk
size or let the controller set it automatically. See “Chunk Size,” page 3–51, for
information about setting the chunk size.
Figure 3–7. Parity Ensures Availability; Striping Provides Good Read Performance
Considerations for Planning a RAIDset
Keep these points in mind as you plan your RAIDsets:
■ A controller can support up to 20 storagesets, consisting of RAIDsets (see
Table 3–1).
CXO5509A
I/O Request
Chunk 1
2
4
3
D
i
s
k
1
0
0
0
0
Chunk 1
4
D
i
s
k
2
0
0
0
0
2
Parity
for
3 & 4
D
i
s
k
3
0
0
0
0
Parity
for
1 & 2
3