Understanding the 'Buffer I/O error' Message During CentOS 7.9 Boot-Up#

Understanding the 'Buffer I/O error' Message During CentOS 7.9 Boot-Up#

Environment

RAID Model: all Graid card
Host Hardware: every platform
Operating System: Linux CentOS 7

Issue

When booting up a CentOS 7.9 system, users may encounter an error message that reads "Buffer I/O error on dev [gpdXn1], logical block 0, async page read". This document will explain the cause of this error message and provide some guidance for users on how to proceed.

Example of the IO error message during CentOS 7.9 booting.

[ 24.240854] Buffer I/O error on dev gpd0n1, logical block 0, async page read [ 24.240868] blk_update_request: I/O error, dev gpd0n1, sector 0 [ 24.240871] Buffer I/O error on dev gpd0n1, logical block 0, async page read [ 24.240960] blk_update_request: I/O error, dev gpd0n1, sector 0 [ 24.240966] Buffer I/O error on dev gpd0n1, logical block 0, async page read [ 24.240987] blk_update_request: I/O error, dev gpd0n1, sector 0 [ 24.240989] Buffer I/O error on dev gpd0n1, logical block 0, async page read [ 24.241018] blk_update_request: I/O error, dev gpd0n1, sector 0 [ 24.241023] Buffer I/O error on dev gpd0n1, logical block 0, async page read [ 24.241094] blk_update_request: I/O error, dev gpd0n1, sector 0 [ 24.241100] Buffer I/O error on dev gpd0n1, logical block 0, async page read [ 24.241164] blk_update_request: I/O error, dev gpd0n1, sector 0 [ 24.241167] Buffer I/O error on dev gpd0n1, logical block 0, async page read

Cause of the Error

The error message indicates that the system is attempting to read from or write to a device during boot-up, and is encountering an error due to a restriction placed on the device. 

Resolution

The /dev/gpdXn1 is the NVMe drive which is already controlled by graid, and it is graid's physical drive path, not the virtual drive device, so graid would restrict user/applications to access those physical drives.

Hence, the "Buffer I/O error" message that users encounter during CentOS 7.9 boot-up is caused by the system attempting to access restricted devices, because those devices are controlled by graid driver and graid driver would restrict assess for safety reasons. While it may be disconcerting to see an error message during boot-up, the error is unlikely to cause any serious issues with the performance or stability of the system. As such, most users can safely ignore the error messages