What is the pre-copy technology of hard disks?
When a storage system detects that a member disk in a RAID group is to fail, the system copies the data on the member disk to a hot spare disk in advance. In this way, the risk of losing data is reduced. This technology is called pre-copy.
The pre-copy technology usually employs the self-monitoring, analysis, and reporting technology (SMART) to monitor the status of hard disks. The SMART detects the failing hard disk and sends an alarm, and then the pre-copy technology backs up the data on the hard disk onto a hot spare disk in advance. Through this fast backup method, the reconstruction time required after a hard disk failure is shortened or even eliminated, and the failure rate of hard disks during reconstruction is also reduced; therefore, the reliability of the storage system is dramatically improved.