Monday, May 13, 2019

RHEL7 - Server is on grub menu

Issue: NOC called about not responding one of the linux server.

What I found: When login through console, server on grub menu.

1. List all disk, disk partition on your system using ls command
grub > ls
(hd0) (hd0,msdos1) hd0,msdos2) ........ so on

Now, you have to find the correct partition

grub > ls (hd0)
error: no such partition.
keep listing, until you find the right filesystem type. You need to know what type of filesystem are you using at your work place. it can be ext or xfs.

grub> ls (hd0,msdos1)
filesystem is ext*
all other partition are xfs, only os is on ext4

lets list the content from it
grub> ls (hd0,msdos1)/
you should be able to see grub2

so this is the right partition. If you didn't find it, keep listing the content of each disk, you will find one.

grub> set boot=(hd0,msdos1)
grub> set prefix=(hd0,msdos1/grub2
grub> insmod normal
grub> normal

system boots and you will be on grub menu. select the right kernel and boot  your system.

If it fails, repeat the same step and select the older kernel, you should be good to go...

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