Refer to the table below for an overview of the different RAID modes, and see the descriptions for details.
|RAID Mode||Capacity||Protection||Speed||Factory Default|
|RAID 0 (FAST)||100%||None||Excellent||Yes|
|RAID 1 (SAFE)||50%||Excellent||OK||No|
RAID 0 (FAST): RAID 0, is the fastest RAID mode. In a RAID 0 array, the available capacities of each drive are added together so that one logical volume mounts on the computer. It offers the best performance but no protection in the case that a drive fails.
RAID 1 (SAFE): RAID 1 provides data safety since all data is written to each drive at the same time. In the event of a single drive failure, data remains available on the other drive. Due to the time it takes to write the data twice, performance is slightly reduced. RAID 1 is a good choice when safety is more important than speed. However RAID 1 also reduces the available drive space by 50% due to the need to write each bit of data on each hard drive.
If your array is protected, ie in a RAID 1/SAFE mode, you can remove a drive without damaging the array and losing data, a process also referred to as “hot-swapping”. However, if you remove a drive from an unprotected (ie RAID 0/FAST) array, you may lose data.
Note that for optimum storage use, the new drive should have equal or greater capacity than the drive it is replacing.