What are RAID 10 (1 + 0) and NESTED RAID (0 + 1) ?

Explanation:

Lets understand RAID (Redundant Array of Independent Disks) LEVELS:

RAID 0 is also called a “stripe set” or a “stripped volume”. This is because data is spitted (striped) between discs – without parity information for redundancy. In other words, RAID 0 does not provide data redundancy. Inter-leveling of data between the disks causes a significant acceleration of read and write operations – due to the paralleling of these operations on all the discs in the array.

RAID 1 (NESTED RAID) is also called a “mirroring” The basic idea of such a solution is the replication (mirroring) of two or more discs. It means that while using RAID 1, an exact copy (or mirror) is created on two or more discs.

RAID 0+1 means arrays implemented as RAID 1, whose elements are RAID 0 arrays. Such implementation has the benefits of RAID 0 speed and RAID 1 fault tolerance with easy recovery.

RAID 1+0 (RAID 10) array is implemented as RAID 0, whose elements are RAID 1. It combines the same advantages of RAID 0 (speed) and RAID 1 (Fault tolerance with easy recovery), but in different way. RAID 1+0 creates a large stripe of small mirrors. After failure of a disk, while it is being replaced, only the small fragment of a whole array is rebuilt.