In datacenters, storage requirements are measured in petabytes. The use of flash memory is imperative to the datacenter. When raw big data access to the datacenter, a random write problem and a memory consumption problem occur. To solve these problems, we suggest a GC algorithm, partial linked garbage collection (PLGC). PLGC organizes a partial linked list based on LBN, when a block needs to do overwrite operation. PLGC deploys DRAM spaces and reduces memory consumption in flash memory.