Lies, mapped drives & device-mapper statistics [Bryn M. Reeves]
Channel: RedHatCzech
Date: 15/02/2016

Linux has provided block device IO statistics for well over 15 years, with familiar tools such as iostat, sar, and PCP able to benefit from the same sets of counter data maintained by the kernel.

Device-mapper, the kernel framework that underpins applications like LVM2, multipath-tools, and dmraid, as well as modern storage virtualisation features, including thin provisioning, and caching has provided its own in-kernel statistics support since 2013 (v3.11).

In addition to the basic statistics already provided by the kernel this includes several new features such as the ability to track a user-defined latency histogram, independent statistics for arbitrary regions of devices, and high-resolution timekeeping.