RAID 1 (Mirroring)

 RAID 1

Data are stored twice by writing them to both the data drive (or set of data drives) and a mirror drive (or set of drives). If a drive fails, the controller uses either the data drive or the mirror drive for data recovery and continuous operation. You need at least 2 drives for a RAID 1 array.

                                     

Img RAID 1

Advantages of RAID 1

·    RAID 1 offers excellent read speed and a write-speed that is comparable to that of a single drive.

·    In case a drive fails, data do not have to be rebuild, they just have to be copied to the replacement drive.

·    RAID 1 is a very simple technology.

Disadvantages of RAID 1

·    The main disadvantage is that the effective storage capacity is only half of the total drive capacity because all data get written twice.

·    Software RAID 1 solutions do not always allow a hot swap of a failed drive. That means the failed drive can only be replaced after powering down the computer it is attached to. For servers that are used simultaneously by many people, this may not be acceptable. Such systems typically use hardware controllers that do support hot swapping.

Ideal use

RAID-1 is ideal for mission critical storage, for instance for accounting systems.