Re: [CentOS] Fwd: 8.2.2004 Quick recovery and fix for unbootable machines with rescue disk
Thanks Greg! Very clear! ___ Sent from MzK's phone. On Sun, Aug 2, 2020, 14:07 Gregory P. Ennis wrote: > Hello all-- > These instructions are somewhat OK but my messed up box is the only one > I've got basically to help with this problem. > > Where can we find "correction" instructions using a "rescue" CD or flash > drive? I understand RedHat provided detailed instructions to supported > customers. > > Thanks. > > ___ > Sent from MzK's phone. > > -- Forwarded message - > From: Alan McRae via CentOS > Date: Sat, Aug 1, 2020, 19:22 > Subject: [CentOS] 8.2.2004 Quick recovery and fix for unbootable machines > To: CentOS mailing list > > > This is a quick recovery and fix for the machines rendered unbootable > after the grub2/shim yum update. > > It is written for CentOS 8.2.2004 but similar should work for any CentOS > 8 or 7 as long as you get the correct shim file, > that is, the one from the latest installation media. > > I am running on an x86_64 architecture (see uname -i). Please use the > correct shim file for your architecture (shim--15-11.el8..rpm) > > I have tested this by breaking a machine and then recovering it. It > works for me. > > I hope someone finds it useful. Let me know. > > Regards > Alan > > HOW TO BOOT AN UNBOOTABLE MACHINE > = > > 1) Download a copy of rEFind. This is a UEFI boot manager. Burn it to a > USB key. > > # wget -O refind.zip > > http://sourceforge.net/projects/refind/files/0.12.0/refind-flashdrive-0.12.0.zip/download > # unzip refind.zip > # cd refind-flashdrive-0.12.0 > # dd if=refind-flashdrive-0.12.0.img bs=4096 of=/dev/sdX (sdX is the > device for your USB key, this will be erased, use the whole device use > sdX not sdX1) > 1800+0 records in > 1800+0 records out > 7372800 bytes (7.4 MB, 7.0 MiB) copied, 0.980893 s, 7.5 MB/s > > 2) Turn off secureboot in your UEFI hardware. > > 3) Boot the USB key. You should get a colourful screen with icons and a > filename below. > > Use the left/right arrow keys to select the correct grubx64.efi. > Hit space to boot. > > Your usual grub menu should appear and the system should boot normally. > > HOW TO FIX THE PROBLEM > = > > 1) We need to downgrade the shim package. Now your system is running get > an older copy of the correct shim package for your architecture > from the CentOS installation media (e.g. > CentOS-8.2.2004-x86_64-dvd1.iso) and install it. > > # mount CentOS-8.2.2004-x86_64-dvd1.iso /mnt > # cd /mnt/BaseOS/Packages > # cp shim-x64-15-11.el8.x86_64.rpm /root > # cd /root > # umount /mnt > > OR > > Get the package from a CentOS mirror: > > # cd /root > # wget > > http://ucmirror.canterbury.ac.nz/linux/CentOS/8.2.2004/BaseOS/x86_64/os/Packages/shim-x64-15-11.el8.x86_64.rpm > > 2) We can now reinstall the older shim package using yum. This will > downgrade the package to the working version. > > # yum install shim-x64-15-11.el8.x86_64.rpm > > Last metadata expiration check: 2:11:11 ago on Sun 02 Aug 2020 11:31:06 > NZST. > Dependencies resolved. > > > === > > = > Package Architecture Version > Repository Size > > === > > = > Downgrading: > shim-x64 x86_64 15-11.el8 > @commandline 647 k > > Transaction Summary > > === > > = > Downgrade 1 Package > > Total size: 647 k > Is this ok [y/N]: y > Downloading Packages: > Running transaction check > Transaction check succeeded. > Running transaction test > Transaction test succeeded. > Running transaction >Preparing : 1/1 >Downgrading : shim-x64-15-11.el8.x86_64 1/2 >Cleanup : shim-x64-15-13.el8.x86_64 2/2 >Verifying: shim-x64-15-11.el8.x86_64 1/2 >Verifying: shim-x64-15-13.el8.x86_64 2/2 > Installed products updated. > > Downgraded: > shim-x64-15-11.el8.x86_64 > > Complete! > > 3) Your system should now boot normally. > > 4) add "exclude=shim*" to /etc/yum.conf to prevent the broken one being > reinstalled. You should now be able to run 'yum update'. Remove the > exclude= when a proper fix becomes available. > > ___ > > Dear List, > > I have had 6 of these problems and am on my way to the office to fix two > more. > > Here is what I did with an installation disc along with the advise from > the posts of Johny > Hughes. So far this has been easy to do and has worked every time. Make
Re: [CentOS] Fwd: 8.2.2004 Quick recovery and fix for unbootable machines with rescue disk
Hello all-- These instructions are somewhat OK but my messed up box is the only one I've got basically to help with this problem. Where can we find "correction" instructions using a "rescue" CD or flash drive? I understand RedHat provided detailed instructions to supported customers. Thanks. ___ Sent from MzK's phone. -- Forwarded message - From: Alan McRae via CentOS Date: Sat, Aug 1, 2020, 19:22 Subject: [CentOS] 8.2.2004 Quick recovery and fix for unbootable machines To: CentOS mailing list This is a quick recovery and fix for the machines rendered unbootable after the grub2/shim yum update. It is written for CentOS 8.2.2004 but similar should work for any CentOS 8 or 7 as long as you get the correct shim file, that is, the one from the latest installation media. I am running on an x86_64 architecture (see uname -i). Please use the correct shim file for your architecture (shim--15-11.el8..rpm) I have tested this by breaking a machine and then recovering it. It works for me. I hope someone finds it useful. Let me know. Regards Alan HOW TO BOOT AN UNBOOTABLE MACHINE = 1) Download a copy of rEFind. This is a UEFI boot manager. Burn it to a USB key. # wget -O refind.zip http://sourceforge.net/projects/refind/files/0.12.0/refind-flashdrive-0.12.0.zip/download # unzip refind.zip # cd refind-flashdrive-0.12.0 # dd if=refind-flashdrive-0.12.0.img bs=4096 of=/dev/sdX (sdX is the device for your USB key, this will be erased, use the whole device use sdX not sdX1) 1800+0 records in 1800+0 records out 7372800 bytes (7.4 MB, 7.0 MiB) copied, 0.980893 s, 7.5 MB/s 2) Turn off secureboot in your UEFI hardware. 3) Boot the USB key. You should get a colourful screen with icons and a filename below. Use the left/right arrow keys to select the correct grubx64.efi. Hit space to boot. Your usual grub menu should appear and the system should boot normally. HOW TO FIX THE PROBLEM = 1) We need to downgrade the shim package. Now your system is running get an older copy of the correct shim package for your architecture from the CentOS installation media (e.g. CentOS-8.2.2004-x86_64-dvd1.iso) and install it. # mount CentOS-8.2.2004-x86_64-dvd1.iso /mnt # cd /mnt/BaseOS/Packages # cp shim-x64-15-11.el8.x86_64.rpm /root # cd /root # umount /mnt OR Get the package from a CentOS mirror: # cd /root # wget http://ucmirror.canterbury.ac.nz/linux/CentOS/8.2.2004/BaseOS/x86_64/os/Packages/shim-x64-15-11.el8.x86_64.rpm 2) We can now reinstall the older shim package using yum. This will downgrade the package to the working version. # yum install shim-x64-15-11.el8.x86_64.rpm Last metadata expiration check: 2:11:11 ago on Sun 02 Aug 2020 11:31:06 NZST. Dependencies resolved. === = Package Architecture Version Repository Size === = Downgrading: shim-x64 x86_64 15-11.el8 @commandline 647 k Transaction Summary === = Downgrade 1 Package Total size: 647 k Is this ok [y/N]: y Downloading Packages: Running transaction check Transaction check succeeded. Running transaction test Transaction test succeeded. Running transaction Preparing : 1/1 Downgrading : shim-x64-15-11.el8.x86_64 1/2 Cleanup : shim-x64-15-13.el8.x86_64 2/2 Verifying: shim-x64-15-11.el8.x86_64 1/2 Verifying: shim-x64-15-13.el8.x86_64 2/2 Installed products updated. Downgraded: shim-x64-15-11.el8.x86_64 Complete! 3) Your system should now boot normally. 4) add "exclude=shim*" to /etc/yum.conf to prevent the broken one being reinstalled. You should now be able to run 'yum update'. Remove the exclude= when a proper fix becomes available. ___ Dear List, I have had 6 of these problems and am on my way to the office to fix two more. Here is what I did with an installation disc along with the advise from the posts of Johny Hughes. So far this has been easy to do and has worked every time. Make sure your system is connected to the network, and know your gateway address and a reasonable ip address of the machine for your network. #1. Boot to tine Install Disc and pick "Recovery Mode" #2. You will be given several options of recover Pick #1 to Continue #3. Use the 'chroot /mnt/sysimage' command to get into your system #4. Activate your network Find the device name you are going
