IBM 86655RY Hardware Maintenance Manual - Page 204

Understanding RAID level-1

Page 204 highlights

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. 1 2 3 4 5 6 7 8 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 194 Hardware Maintenance Manual: Netfinity 7600 - Type 8665 Models 1RY, 2RY

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194
Hardware Maintenance Manual: Netfinity 7600
Type 8665 Models 1RY, 2RY
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
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.
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