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RAID 1 (mirroring)
A RAID 1 array contains two hard drives where the data between the two is mirrored in real time. Because all of the data is duplicated, the operating system treats the usable space of a RAID 1 array as the maximum size of one hard drive in the array. For example, two 400 GB hard drives in a RAID 1 array will appear as a single 400 GB hard drive to the operating system.
The primary benefit of RAID 1 mirroring is that it provides good data reliability in the case of a single disk failure. When one disk drive fails, all data is immediately available on the other without any impact to the data integrity. In the case of a disk failure, the computer system will remain fully operational to ensure maximum productivity.
The performance of a RAID 1 array is greater than that of a single drive because data can be read from multiple disks - the original and the mirror - simultaneously. Disk writes do not realize the same benefit because data must first be written to one drive, then mirrored to the other.
| Minimum Disks: |
2 |
| Advantage: |
100% redundancy of data. One disk may fail, but data will continue to be accessible. A rebuild to a new disk is recommended to maintain data redundancy. |
| Fault-tolerance: |
Excellent - disk mirroring means that all data on one disk is duplicated on another disk. |
| Application: |
Typically used for smaller systems where capacity of one disk is sufficient and for any application(s) requiring very high availability. | |
This applies to:
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