Advances in flash memory SSD technology for enterprise database applications

Abstract

The past few decades have witnessed a chronic and widening imbalance among processor bandwidth, disk capacity, and access speed of disk. According to Amdhal's law, the performance enhancement possible with a given improvement is limited by the amount that the improved feature is used. This implies that the performance enhancement of an OLTP system would be seriously limited without a considerable improvement in I/O throughput. Since the market debut of flash memory SSD a few years ago, we have made a continued effort to overcome its poor random write performance and to provide stable and sufficient I/O bandwidth. In this paper, we present three different flash memory SSD models prototyped recently by Samsung Electronics. We then show how the flash memory SSD technology has advanced to reverse the widening trend of performance gap between processors and storage devices. We also demonstrate that even a single flash memory drive can outperform a level-0 RAID with eight enterprise class 15k-RPM disk drives with respect to transaction throughput, cost effectiveness and energy consumption.

Scan and Join Optimization by Exploiting Internal Parallelism of Flash-Based Solid State Drives

“…In this way, native command queuing (NCQ) mechanisms of the host interface can generate favorable I/O patterns to the internal architecture [14]. In this paper, we mainly use multi-thread processing technique to produce multiple parallel I/Os at the same moment.…”

ADAPT: Efficient workload-sensitive flash management based on adaptation, prediction and aggregation

“…Typically, the log space is about 3% of all space [12] [15]. It is usually partitioned into a sequential area for sequential writes and a random area for random writes.…”

Transactional In-Page Logging for multiversion read consistency and recovery

“…Recent advances in flash memory SSD technology have increased the I/O bandwidth and throughput of storage devices based on flash memory significantly, and it has been demonstrated that this new storage medium can be used to improve the throughput of large scale OLTP systems by orders of magnitude with much less energy consumption [21], [1]. This impressive development has been realized by various research and development endeavors for better hardware and software such as multi-channel architecture, over-provisioned capacity, large DRAM buffer, flash translation layers, wear leveling algorithms, and so forth.…”

“…Due mainly to their superior characteristics such as high throughput for random I/O and low energy consumption, flash memory SSDs are now considered crucial or even indispensable for building high performance large scale data systems. As the preliminary experience and analysis show, flash memory SSDs outperform magnetic disk drives with respect to transaction throughput and energy conservation for OLTP systems [1]. Therefore, a largescale adoption of flash memory SSDs in database machines [2] and tier zero storage for data centers [3] is not surprising any more.…”