System updated the next day booted by the kernel that was installed. Based on a tutorial, I tried to burn the ISO image of the Arch Linux on a USB key using the command "sudo dd". Having problems, formatted the flash drive and could not write files to it. I tried changing the permissions and ownership of the folder where it was mounted, but got no success. Since then, every time I save files on a flash drive - tested with several different USB sticks that work perfectly in other operating systems - necessary to run the command "sync", otherwise the changes are discarded to remove the device.
How to solve this problem?
Already, thanks to all!