RAID 1+0 is also known as RAID 10 (Ten) or RAID 1/0. RAID 1+0 is also called striped mirror.
The basic element of RAID 1+0 is a mirrored pair. This means that data is first mirrored and then both copies of the data are striped across multiple disk drive pairs in a RAID set. When replacing a failed drive, only the mirror is rebuilt. In other words, the storage system controller uses the surviving drive in the mirrored pair for data recovery and continuous operation. Data from the surviving disk is copied to the replacement disk