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How to resolve Kernel Panic?
Hi I have a KVM VPS.
What am I supposed to do when this happens?
http://i.imgur.com/xnDqW4H.png
Never had this happen before.
All I did was login to SSH and typed reboot, and then my VPS never came back online, then I went to console and I see that.
I tried rebooting the VPS multiple times from SolusVM but it always gives that error.
OS I have running is Centos 6 64bit
Comments
Did you just upgrade the kernel?
Best idea would be to contact your VPS provider.
If you've updated your system recently with yum upgrade / update then it might have installed a new kernel. Try to get back in through console and then check to see if there's a new version of the kernel in boot.
I ran
yum update -y
and then rebooted my VPS once that completed.
Yeah so centos might have installed a new kernel with that update, and then when you rebooted it would have tried to boot the new kernel. I've had the same problem before where centos did this to me resulting in a kernel panic.
I tried. They told me to fix this my self.
http://i.imgur.com/V8dY7VZ.png
Can you please provide me the steps to fix it?
Go to console / vnc. Reboot the machine, then in console when it boots up you'll see a list of kernels, select the 3rd one down usually. The first one will be the new failing kernel
You're definitely not going to get anywhere going that route.
Log in to VNC, reboot the machine. As it starts up keep pressing the up/down key and it should give you the option to choose the kernel to boot into from the list. Choose your previous kernel version (it will not be the top one and will have an earlier number). Once done, edit grub.conf and move that kernel into the default (0) position.
When I reboot the VPS it disconnects me from VNC, and as soon as I reconnect to VNC the screen is already at the Kernel Panic - Not Syncing screen.
Have you changed the HDD driver (VirtIO on / off) after the VPS was installed? If yes, return it to the previous state and try again.
I never changed that setting.
Disk Driver has always been virtio
How are you connecting to VNC? Don't use the Java trash. Use a VNC client.
Can you boot a rescue CD or something? Then mount the filesystem, chroot and rerun grub.
Do not use the reboot in SolusVM but the ctrl-alt-del button in the java VNC client. This will help you fix that problem.
I was using the Java, I tried using VNCViewer and as soon as it connects, there's a black screen, and then VNCViewer just closes.
http://i.imgur.com/idqH8GQ.png
I tried it both from my Mac and my Windows PC.
Kernel Xanax
Use the SolusVM console, that'll give you access even when its down since it's a KVM
In that case, contact the host and ask them specifically to help with the VNC issue. If they are still unwilling to help you (I am sure this may be the case), boot into a rescue CD, mount the filesystem then edit the grub file.
Edit, also just thinking. Connect a VNC session, then instead of rebooting, send a reset signal (CTRL-ALT-DEL) see if that helps.
I just tried that now. I pressed the ctrl-alt-del button in the console here http://i.imgur.com/VsxarAG.png
It's not doing anything. Tried pressing it once and waited ~ 30 seconds.
Then I tried pressing it a few times, still no difference.
The SolusVM Console closes when the VPS goes offline, by the time it reconnects to VNC the screen is already at the kernel panic screen, so I don't have the ability to change kernel or anything.
& Using the ctrl-alt-del button in console like @MCHPhil said does nothing
That is the one catch I forgot about :S. If there is no data it may be simpler to reinstall or try the suggestion of mounting one of the recovery ISO available. If you need/want to try a different ISO just ticket.
No data? There is a kernel panic so obviously some data there.
Do the reboot then straight away go to the console. Infact, what I do is open 2 tabs in firefox, one doing the reboot and the other having the console ready to open.
Tried it a few times and finally got in on time.
These are the 2 options i have http://i.imgur.com/TvWi53G.png
I used the 2nd one and my VPS now works.
What should I change so it always uses the 2nd one instead of the 1st one?
Go for the second one, the first one is the one it loads by default it's the one that is panicing.
Is it obvious he has no backup or any data on the VM that is essential? Maybe I missed that? I'm trying to give him options.
The second one worked, I'm logged into the VPS now. What should I change so it loads the 2nd one by default?
Update your grub boot loader, should be lots of info on google on how to for centos. I think it's just a case of updating the grub.cfg file, but looking for a guide is probably best if you're not sure. Also lookup how to disable kernel updates from yum (I can't remember how I usually do it).
Inside grub configuration you should be able to see where the default is set. It will be DEFAULT=0 (likely)