1. S5100 controllers recognize disks through backplanes of disk enclosures. By replacing the original disk enclosure with a new one without changing disk positions, only the backplane of the new disk enclosure can be recognized, causing the RAID group failure. In this condition, only the information about the new enclosure is recorded by controllers. 2. By inserting the backplane of the original disk enclosure into the new disk enclosure and then powering on the storage device, all original configuration information about disk enclosures, RAID groups, and LUNs can be properly recognized. However, the previously recorded information about the new disk enclosure exists. 3. If the original disk enclosure has configuration information, users need to modify the MAC address of the expansion enclosure before replacing the original disk enclosure to ensure that only the latest enclosure can be recognized by controllers.