The Necessary Death of the Block Device Interface
Solid State Drives (SSDs) are replacing magnetic disks as secondary storage for database management, as they offer orders of magnitude improvement in terms of bandwidth and latency. In terms of system design, the advent of SSDs raises considerable challenges. First, the storage chips, which are the basic component of a SSD, have widely different characteristics - e.g., copy-on-write, erase-before-write and page-addressability for flash chips vs. in-place update and byte-addressability for PCM chips. Second, SSDs are no longer a bottleneck in terms of I/O latency forcing streamlined execution throughout the I/O stack. Finally, SSDs provide a high degree of parallelism that must be leveraged to reach nominal bandwidth.