“Buffer I/O error on dev sr0, logical block 0, async page read” when using USB dongle

A while ago a faced a problem with USB modem. There were tons of similar error messages during boot and due to udev spamming, the boot process took VERY long.

The message looked like so:

Buffer I/O error on dev sr0, logical block 0, async page read

The reason is USB dongle, which hides in itself multiple devices, including flash storage device with drivers. The storage device tries to run during boot, which cause the error above.

If you don’t have сdrom (virtual or physical) and feel OK to block every cdrom device in your system, then solution is simple. You can simply eject each attached cdrom using udev rule.

nano /etc/udev/rules.d/rndis.rules

KERNEL=="sr0", ACTION=="add", RUN+="/usr/bin/eject /dev/sr0"

Then, update initramfs.

update-initramfs -u

That’s all. Now you can reboot to check there are no new errors related to your dongle.