IBM Netfinity ServeRAID-4H Ultra160 User Reference page 17

Create an array using the two physical drives.
Then, create a logical drive within that array.
The data is striped across the drives, creating blocks.
Notice that the data is striped across all the drives in
the array, but no redundant data is stored.
A physical drive failure within the array results in loss of data in the logical drive
assigned RAID level-0, but only in that logical drive. If you have logical drives
assigned RAID level-1, 1E, 5, or 5E in the same array, they will not lose data.
Note: If you have an array that contains only one physical drive, you can assign
only RAID level-0 to the logical drive in that array.
When you replace a failed drive, the ServeRAID controller can rebuild all the RAID
level-1E and RAID level-5E logical drives automatically onto the replacement
physical drive. However, any data stored in a failed RAID level-0 logical drive is
lost.
Although the risk of data loss is present, you might want to assign RAID level-0 to
one of the logical drives to take advantage of the speed this RAID level offers. You
can use this logical drive to store data that you back up each day and for which
safety is not of primary importance, that is, data that you can re-create easily. You
also might want to use a RAID level-0 logical drive when you require maximum
capacity.
Understanding RAID level-1
RAID level-1 provides 100% data redundancy and requires only two physical drives.
With RAID level-1, the first half of a stripe is the original data; the second half of a
stripe is a mirror (that is, a copy) of the data, but written to the other drive in the
RAID level-1 array.
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Chapter 1. Getting started
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