How to persistently set nr_requests using UDEV rules

Last updated on JUNE 24, 2016

Applies to:

Goal

The nr_requests is a parameter for block device, it controls maximum requests may be allocated in the block layer for read or write requests, the default value is 128.
Occasionally, it may be suggested to adjust the value, generally speaking:
Increasing the value will improve the I/O throughput, but will also increase the memory usage.
Decreasing the value will benefit the real-time applications that are sensitive to latency, but it also decreases the I/O throughput.

This article elaborate how to set the parameter permanently across system reboots.

Solution