Utilizing micro-architecture parallelism to hide reclaiming operations for NAND multi-channel SSDs

Due to the unique erase-before-write characteristic of flash memories, flash-based solid-state disks (SSDs) use out-of-place update and require a garbage collection process to recycle invalid data space. This process brings extra operations and latencies, causing I/O blocking and performance degradation, especially when the device is close to be full. In this work, we use a parallel-unit-aware allocation policy for the internal migrating write and incoming requesting write, scheduling and packing all the operations together to utilize the micro-architecture parallelism of multi-channel SSDs. Trace-driven simulations reveal that the proposed design reduces 33.31% of response time, on average, thus improves the device performance.