IBM ServeRAID, User Reference

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The following illustration is an example of a RAID level-5 logical drive.
Start with four physical drives.
Create an array using three of the
physical drives, leaving the fourth as a
hot-spare drive.
Then create a logical drive within that
array.
The data is striped across the drives,
creating blocks.
Notice that the storage of the data
parity (denoted by *) also is striped,
and it shifts from drive to drive.
A parity block (*) contains a
representation of the data from the
other blocks in the same stripe. For
example, the parity block in the first
stripe contains data representation of
blocks 1 and 2.
1 2
3
5
7
4
6
8
2
*
*
*
*
If a physical drive fails in the array,
the data from the failed physical drive
is reconstructed onto the hot-spare
drive.
2
3
5
4
8
2
*
*
*
1
7
6
*
Chapter 3. Understanding RAID technology
27