Notice that the data on the drive on the right is a copy of the data on the drive on the left.
RAID level-1 uses data mirroring. Two physical drives are combined into an disk group, and data is striped across the array. 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 it is written to the other drive in the RAID level-1 disk group.
RAID level-1 provides data redundancy and high levels of performance, but the storage capacity is diminished. Because the data is mirrored, the capacity of the logical device when assigned RAID level-1 is 50% of the disk group capacity.
RAID level-1 requires two physical drives.
The following illustration shows an example of a RAID level-1 logical device.
| Start with two physical drives. | |
| Create a disk group using the two physical drives. | |
| Then create a logical device within that disk group. | |
| The data is striped across the drives,
creating blocks.
Notice that the data on the drive on the right is a copy of the data on the drive on the left. |
|
With RAID level-1, if one of the physical drives fails, the controller switches read and write requests to the remaining functional drive in the RAID level-1 disk group.
RAID level-1 offers the following advantages and disadvantages.
| Advantages | Disadvantages |
|---|---|
|
Allows only 50% of the physical drive storage capacity to be used |
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