Request-Based Device Mapper and Multipath Dynamic Load BalancingKiyoshi Ueda (firstname.lastname@example.org)
Storage multipathing is inevitable for enterprise system and dm-multipath is the solution added since 2.6.12 kernel. However, dm (device-mapper) is implemented above the IO scheduler, which makes it difficult to make load balancing decision without knowing too much about the other layer. The presentation focuses on a generic solution of moving dm-multipath below the IO scheduler, starting from overview of block IO and dm, analysis of the problems, exploring several approaches to overcome them including changes to block layer and performance test results.
Expected audiences are Linux developers who are interested in dm and block layer and users of storage multipathing with Linux. Basic knowledge on Linux storage components is needed.