Ubuntu failed to start and appeared missing modules

Refer to these two articles to solve the problem:

Ubuntu Startup Stop issues (http://www.linuxidc.com/Linux/2011-06/37950.htm)

PowerEdge T410 Installation ubuntu14.04/14.10 error (http://blog.cnrainbird.com/index.php/2015/01/08/poweredge_t410_an_zhuang_ ubuntu14_04_14_10_cuo_wu_yi_ze/)

Phenomenon

The operating system that was used was ubuntu14, and a problem occurred on a Dell server.

At the start of the system startup screen, the following information appears and stops booting. (Note that this is a problem with the system startup process, not the installation process, after the system is installed.) ）

Gave up waiting forroot device. Common problems:–boot args (cat/proc/cdmline) –check rootdelay= (Did the system waitLongEnough?) –check Root= (Did the system wait forThe right device?) –missing modules (cat/proc/modules; LS/Dev) ALERT! /DEV/DISK.BY-UUID/9D77FCD2-5FC1-419D-939C-AF16BE94FD34 does not exist. Dropping to a shell!BusyBox v1.21.1(Ubuntu1:1.21.0-1UBUNTU1) built-inch(Ash) Enter ' Help ' fora list of BUILTIN commands. (INITRAMFS)

Reason

By reference: The Rootdelay setting in the Grub boot parameter is too short, causing the system to start looking for the root partition without loading the device driver properly, causing the/root partition to be found.

Solve

When the system starts to stop at this interface, enter "Exit" and return, the system will continue to boot, to successfully enter the system. For Ubuntu systems, you can fix them as follows.

1. Edit the/etc/default/GRUB file in grub_cmdline_linux This configuration item plus rootdelay= : grub_ Cmdline_linux= "rootdelay=″ Description: 90 means the time delay, according to their own actual situation, such as my own server I will 90 to 60 can also be, maybe a little shorter also, but did not try.  2. Execute command: update-grub is used to update the boot menu to this has been completely resolved, the next boot will not appear this problem. 

The above fix is essentially to modify the boot parameters of grub, and for other Linux distributions, find a way to modify the grub corresponding boot parameters.

For example, the Grub boot menu has one of the following commands for a particular menu item:

Linux/boot/vmlinuz-4.4.0-31-generic root=uuid=8cfd2963-4616-4c18-bb1f-c6f6e8eaa9ed ro Hugepagesz=2M hugepages=1024 Net.ifnames=0 biosdevname=0

Only need to add rootdelay=xx after this item, XX is the delay time set by oneself. (Note that there is a space between the Rootdelay parameter and the preceding parameter)

Linux/boot/vmlinuz-4.4.0-31-generic root=uuid=8cfd2963-4616-4c18-bb1f-c6f6e8eaa9ed ro Hugepagesz=2M hugepages=1024 Net.ifnames=0 biosdevname=0 rootdelay=90

Ubuntu failed to start and appeared missing modules