Recover or restore initramfs file in RHEL or CentOS 7

What if "initramfs" file is deleted or corrupted on your RHEL or CentOS 7 ?

Lets know what is initramfs image ?

The INITial RAM Disk (initrd) is an initial root file system that usually get mounted prior to when the real root file system gets available. The "initrd" image is also known as "initramfs (Initial RAM FileSystem)" from RHEL 6.x onwards. The initrd/initramfs gets bound to the kernel and loaded as part of the kernel boot procedure. The kernel then mounts this initrd/initramfs as part of the two-stage boot process to load the modules to make the real file systems available and mount's the real root file system.

Initrd/Initramfs image provides the capability to load a RAM disk by the boot loader. This RAM disk can then be mounted as the root filesystem and programs can be run from it. Afterwards, a new root file system can be mounted from a different device. The previous root filesystem which was mounted from initrd/initramfs is then moved to a directory and can be subsequently unmounted.


Yes, their are chances that either you might have accidentally deleted "initramfs" file from the /boot partition or it is corrupted due to some reason. 

Then boot process will get interrupted and you will see below error:


error: file '/initramfs-3.10.0-957.el7.x86_64.img' not found.

Good news is you can still recover this "initramfs" by following below steps:

Step 1 : Mount RHEL or CentOS 7 ISO image on your physical server and boot from it. In case you are using HPE Prolient server you can mount this ISO image on iLO, if this is virtual environment then mount it accordingly and reboot server or VM from ISO. Once rebooted you will see below options:


Step 2 : Scroll down and select "Troubleshooting" option from menu and PRESS "Enter"


Step 3 : Select "Rescue a CentOS system" and press ENTER:


Step 4 : Press ENTER key again to continue:


Step 5 : To continue, Type "1" and press ENTER, this will bring you to rescue mode, chroot sysimage filesystem using below command:

# chroot /mnt/sysimage



Step 6 : Next step is to verify if "initramfs" file is located in /boot directory. If not then we will generate a new one.

 # dracut -f /boot/initramfs-$(uname -r).img $(uname -r)



Once file is generated, exit from the chroot and again exit to reboot the server ==> ISSUE FIXED.

Comments

  1. RobbyNovember 27, 2019 at 2:24 PM

    Looks pretty awesome, thanks!

    ReplyDelete
  2. Micheal AlexanderFebruary 14, 2021 at 2:13 PM

    Wow what a great blog, i really enjoyed reading this, good luck in your work. Antigen Test Ket

    ReplyDelete
  3. KaKaMarch 19, 2021 at 3:14 PM

    Very excellent blog post. I am thankful for your blog post.
    odzyskiwanie danych

    ReplyDelete
  4. SacheenBMay 30, 2021 at 2:42 PM

    Thanks Ashish, Keep up the great work

    ReplyDelete
  5. UnknownNovember 18, 2021 at 9:10 PM

    This saved the day, thank you!

    ReplyDelete
  6. TabrezMarch 28, 2022 at 10:37 PM

    is it for RHEL7 also...bcoz in RHEL7 we have rescue mode and i think we dont need to attach ISO ...we can just reboot the server and select rescue mode.

    ReplyDelete

Post a Comment

Popular posts from this blog

Space reclamation / UNMAP on RHEL or CentOS 7

What is Space Reclamation? This feature supports Thin Provisioned environment, and it is the process of freeing space from the storage system that has already been freed from the host file system. A host file system contains metadata to keep track to know which blocks are available to store new data and which blocks contain actual data and must not be overwritten. This metadata is stored within the LUN. When a file is deleted in the host file system, the file system metadata is updated to mark that file's blocks as free space. Total file system free space is then recalculated to include the newly-freed blocks. To the storage system, these metadata updates appear no different than any other writes being performed by the host. Therefore, the storage system is unaware that any deletions have occurred. What is Unmapping? Unmapping is a process which de-allocates relationship between LBA and a physical block in a logical unit. Reclamation within RHEL and CentOS: RHEL / Ce
Read more

How to recover /boot partition on RHEL or CentOS 7?

Image
What if mistakenly you delete all the files from /boot partition or files got corrupted due to some reason ! You will see below error on the screen at the time of system boot. But there is a way to recover /boot partition files :) Follow these steps to recover /boot partition : Step 1 :  Mount RHEL or CentOS 7 ISO image on your physical server and boot from it. In case you are using HPE Prolient server you can mount this ISO image on iLO, if this is virtual environment then mount it accordingly and reboot server or VM from ISO. Once rebooted you will see below options: Step 2 :  Scroll down and select "Troubleshooting" option from menu and PRESS "Enter" Step 3 :  Select "Rescue a CentOS system" and press ENTER: Step 4 :  Press ENTER key again to continue: Step 5 :  To continue, Type "1" and press ENTER, this will bring you to rescue mode, chroot sysimage filesystem using below command:
Read more