Updated dracut packages that fix a bug are now available for Red Hat Enterprise Linux 6.
The dracut package is an event-driven initramfs generator infrastructure based around udev. The initramfs is loaded together with the kernel at boot time and initializes the system, so it can read and boot from the root partition.
Prior to this update, the udev rules used by dracut may have caused the merged logical volume management (LVM) snapshots to be accessed. Consequent to this, I/O errors appeared in the log. With this update, dracut's internal udev rules have been updated to ignore those internal devices, and dracut now works as expected.
Users of dracut are advised to upgrade to these updated packages, which fix this bug.