The constraints of magnetic versus flash disk capabilities in big data analysis

Abstract

Solid state disks (or flash disks) are decreasing in cost per gigabyte and are being incorporated into many appliances, such as the Oracle Database Appliance [8]. Databases--and more specifically data warehouses--are often utilized to support large scale data analysis and decision support systems. Decision makers prefer information in real time. Traditional storage systems that are based on magnetic disks achieve high performance by utilizing many disks for parallel operations in RAID arrays. However, this performance is only possible if requests represent a reasonable fraction of the RAID stripe size, or I/O transactions will suffer from high overhead. Solid state disks have the potential to increase the speed of data retrieval for mission critical workloads that require real time applications, such as analytic dashboards. However, solid state disks behave differently than magnetic hard disks due to the limitations of rewriting NAND flash based blocks. Therefore, this work presents benchmark results for a modern relational database that stores data on solid state disks, and contrasts this performance to a ten disk RAID 10 array, a traditional storage design for high performance database data blocks. The preliminary results show that a single solid state disk is able to outperform the array for queries summarizing a data set for a variety of OLAP cube dimensions. Future work will explore the low level database performance in more detail.