High-performance SMR drives with dm-zoned Caching

SMR drives have a very demanding programming model, requiring the host software to format write requests withing very strict limits. This typically imposes a performance penalty when writing to SMR drives such that the nominal performance is hard to achieve. The existing dm-zoned device-mapper target implements an internal caching using random zones; while this allows for unmodified host software to run on SMR drives the performance impact is even more severe. In this talk I will present an update to dm-zoned, which extends the current implementation to use additional drives, either as a cache device or as additional zoned devices. This allows to saturate the SMR drives without having to modify the host software. By using a fast cache device like NV-DIMM one can easily scale the dm-zoned device across several SMR drives, presenting tens of terabytes to the application with near-native NV-DIMM speeds. I will present the design principles of this extension, and providing a short demo for showing the improvements.

Learning Objectives

Use dm-zoned to ease SMR drive usage,Increase SMR drive performance by using cache devices,Scaling SMR drives by using NV-DIMM cache devices