RAID is a method of utilising space on multiple hard disks. Our NAS devices support the following RAID types:

• RAID 0
• RAID 1
• RAID 5 (RAID 5 + Hot Spare)
• RAID 6
• RAID10

We suggest using disks of the same size when creating RAID arrays. Where disks of different sizes are used, the overall available space will be based on the size of the smallest disk, or the existing size of the array.

• RAID 0 needs a minimum of 2 hard disks and uses the all available space on the disks, and provides no redundancy.

• RAID 1 needs (a minimum of) 2 hard disks and mirrors the information from one disk to another. RAID 1 can tolerate the failure of 1 hard disk.

If disks of different sizes are used, the overall space available will be that of the smaller disk. The remaining space on the larger disk can be formatted as a different volume that will NOT be part of the RAID array.

• RAID 5 (or RAID 5 + Hot Spare) needs a minimum of 3 hard disks, and can tolerate the failure of 1 hard disk.
If disks of different sizes are used then the overall space will be a multiple of the size of the smallest disk in the array. The remaining space on the larger disk(s) can be formatted as a different volume that will NOT be part of the RAID array.

• RAID 6 needs a minimum of 4 drives and can tolerate the failure of 2 disks.
If disks of different sizes are used then the overall space will be a multiple of the size of the smallest disk in the array. The remaining space on the larger disk(s) can be formatted as a different volume that will NOT be part of the RAID array.

• RAID 10 needs a minimum of 4 disks and can tolerate the failure of 1 disk in each array span.
As with RAID 1, if disks of different sizes are used then the overall space will be twice the size of the smallest disk in the array.

With RAID 1, 5, 6 and 10, it is possible for the NAS to automatically rebuild the ar-ray when the failed disk is replaced.