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: 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 5: In RAID 5, data is striped across all disks (minimum of three) and a parity block for each data block (P in the illustration below) is written on the same stripe. If one physical disk fails, the data from the failed disk can be rebuilt onto a replacement disk. No data is lost in the case of a single disk failure, but if a second disk fails before data can be rebuilt to a replacement drive, all data in the array will be lost.
RAID 5+Spare: RAID 5+Spare is a RAID 5 array in which one disk is used as spare to rebuild the system as soon as a disk fails. At least four disks are required. If one physical disk fails, the data remains available because it is read from the parity blocks. Data from a failed disk is rebuilt onto the hot spare disk. When a failed disk is replaced, the replacement becomes the new hot spare. No data is lost in the case of a single disk failure, but if a second disk fails before the system can rebuild data to the hot spare, all data in the array will be lost.
RAID10: RAID 10 (also called RAID 1+0) is another RAID level that combines the attributes of other levels, specifically RAID 1 and RAID 0. It is a “stripe of mirrored sets”, meaning that data is striped across two mirrored arrays. The striping occurs between arrays and the mirroring occurs within the same array, which makes the rebuilding very fast.
If your array is protected, ie in a RAID 10, 5, or 5+spare mode, you can remove a drive without damaging the array and losing data even when the product is turned on, a process also referred to as “hot-swapping”. However, if you remove a drive from an unprotected (ie RAID 0) 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.