SSD Caching: Device-Mapper- and Hardware-based solutions compared

von Werner Fischer (Thomas-Krenn.AG), Georg Schönberger (Thomas-Krenn.AG)

Thursday, 24.05.2012, London, 14:00-14:45 Uhr

SSDs provide never-seen I/O performance for non-volatile data storage. Especially their random I/O performance is drastically higher compared to conventional hard drives. But unfortunately also their price per gigabyte is higher too and their possible storage capacities do not reach traditional disks. To build multi-terabyte storages, pure SSD solutions just get too expensive.

But is there a way to benefit both from SSDs I/O performance and the price of traditional disks? The answer is: yes, when you use SSDs just as a cache in front of your traditional disks. This is especially useful in database environments, when the working set of the database does not fit in main memory. Another use case are container solutions like OpenVZ or LXC where you can host lots of guest systems on a single machine, keeping their most accessed data in the SSD cache and therefor reducing the I/O bottleneck often seen on such systems.

There are already multiple solutions around which implement SSDs as a cache: proprietary hardware-based RAID controller solutions like LSI CacheCade or Adaptec maxCache, Intel's Smart Response Technology for their Z68 chipset or different open source solutions, which work as device mapper target. They include FlashCache, SSDCache, DM-Cache and Bcache.

In this talk we compare those solutions, including how easy they are to use and how they perform.

Über den Autor Werner Fischer:

Werner Fischer is a technology specialist at Thomas-Krenn.AG since 2005 and chief editor of the Thomas Krenn Wiki. His current main focus is hardware-monitoring and I/O optimization, especially with Flash-based storage. Besides that Werner mainly deals with virtualization and high availability. He is a regular speaker about all these topics at various conferences, including OSDC, OSMC, LinuxTag, LinuxCon Europe, Profoss, Open Source Meets Business, Security Forum Hagenberg and other conferences.

Before joining Thomas Krenn in 2005, Werner worked at IBM in Germany and Austria. Together with other IBMers he wrote two IBM Redbooks in the HA and storage area. Werner holds a graduate degree in computer and media security from the University of Applied Sciences of Upper Austria in Hagenberg.

Über den Autor Georg Schönberger:

Georg Schönberger is a Technology Specialist at Thomas Krenn. He is a regular contributor of new articles for the Thomas Krenn Wiki and provides support in terms of information security questions.. As his previous engagement was programming-driven he is still operating in this area, e.g. writing hardware-monitoring plugins. Further fields of interest reach from GPU computing including CUDA programming to information security management.