Linux Multipathing

Linux multipathing provides io failover and path load sharing for multipathed block devices. In this paper, we provide an overview of the current device mapper based multipathing capability and describe Enterprise level requirements for future multipathing enhancements. We describe the interaction amongst kernel multipathing modules, user mode multipathing tools, hotplug, udev, and kpartx components when considering use cases. Use cases include path and logical unit re-configuration, partition management, and path failover for both active-active and active-passive generic storage systems. We also describe lessons learned during testing the MD scheme on high-end storage.

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