Single level RAID 1 is the simplest RAID configuration requiring just two disks of equal size. When data is written to a RAID 1 array, it is written to one disk and simultaneously copied or "mirrored" to a redundant disk. If one drive of a RAID 1 array fails, the system will continue to operate using the redundant disk.
Raid 1 arrays are built for security. Instead of writing data to 1 disk, RAID 1 arrays write the same data to two disks. The following is a simple example illustrating how RAID 1 works.
Say we have a text file that consists of four characters "ABCD" and a RAID 1 array of two disks.
Here's a data representation of our text file:
Text in file
| Text in file |
A |
B |
C |
D |
| ASCII code |
4 |
1 |
4 |
2 |
4 |
3 |
4 |
4 |
| Raw binary data |
0
1
0
0
|
0
0
0
1
|
0
1
0
0
|
0
0
1
0
|
0
1
0
0
|
0
0
1
1
|
0
1
0
0
|
0
1
0
0
|
Here's what happens when we save the file:
The data written to disk 1 is copied to disk 2. The on one disk is a mirror of the other.
| | DISK 1 | DISK 2 |
| A |
0
1
0
0
0
0
0
1
|
0
1
0
0
0
0
0
1
|
| B |
0
1
0
0
0
0
1
0
|
0
1
0
0
0
0
1
0
|
| C |
0
1
0
0
0
0
1
1
|
0
1
0
0
0
0
1
1
|
| D |
0
1
0
0
0
1
0
0
|
0
1
0
0
0
1
0
0
|
As you can see, a RAID 1 system is very simple. Recovering data from a simple RAID 1 system is exactly the same as recovering data from a single disk.
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Continue reading about RAID Arrays at one of our informational pages listed below.
