A method includes filling a cache memory with a test pattern and forcing a write-back of the cache memory to a region of memory. The source of additional weight may have a mass per unit length between about three times and about eight times the basis weight of the base sheet. Technical solutions of the present disclosure can save bandwidth resources and reduce the workload for upgrading software. When assembling, the drive bracket stays in the chassis, the confining patch is engaging in the confining hole, the elastic patch presses the baffle; when disassembling the drive bracket is pushed outwardly by the elastic patch pressing the baffle.