GCL: An Optimization Strategy for Eliminating I/O and Garbage Collection Conflicts in SSD RAID

Faced with large-capacity storage requirements, the SSD RAID-5 system offers fast I/O performance and fault tolerance. However, as the space management module of SSDs, the complexity of the garbage collection (GC) operating mechanism is the primary cause of the decline in read and write performance. Furthermore, this situation will only become more severe in SSD RAID systems. This article proposes a garbage collection lock strategy based on SSD RAID - 5, named GCL (Garbage Collection Lock). This strategy restricts the number of SSDs that need garbage collection to one each time and utilizes the fault-tolerance mechanism of RAID-5 to reconstruct read operations that need to be carried out on the locked device. Additionally, for write operations, we prioritize caching the locked device write requests during garbage collection. Through a series of simulation tests on several real disk workloads, we have shown that GCL can effectively improve system performance. Compared with RR, GCL increased the reconstruction operation rate by an average of 23% and reduced the overall response time by an average of 5.6%.