DTB+: An enhanced data management strategy for efficient RMW reduction in IMR drives

The emerging Interlaced Magnetic Recording (IMR) technology not only achieves higher storage density than SMR, but also significantly reduces rewrite overhead by dividing tracks into bottom and top tracks and organizing them in an interlaced fashion. However, frequent updates to the bottom track can trigger a large number of Read-Modify-Write (RMW) operations during high disk space utilization, which can severely degrade the I/O performance. Addressing this issue, this paper proposes an interlaced translation layer named DTB+ to improve the write performance of IMR disks. Firstly, a workload-sensitive track heat analysis mechanism is introduced to intelligently place data to reduce track rewrite probability. Simultaneously, the zero-incremental cost region is selectively used to construct a twin-buffer architecture to reduce RMW operations. In addition, an adaptive space allocation engine based on reinforcement learning was developed to flexibly allocate and reclaim space within the twin-buffer, improving disk resource utilization. Finally, establish a flexible evicted-data transfer zone to delay the writeback operations of interference data, further reducing the additional overhead. Experimental results indicate that compared with the state-of-the-art studies, DTB+ can reduce RMWs by 63.00% and additional I/O operations by 57.41%, decrease the average write latency by 37.77%, and lower the tail latency by 53.95%.