Tag Archives: linux

Kernel Panic in CentOS 6.7 After Kernel Upgrade

I ran into this issue after updating with Yum, on the next reboot, the system wouldn’t boot properly. In my case, the error I received was

Kernel panic – not synching:

VFS: Unable to mount root fs on unknown-block(0,0)

 Picture of the full error below:

error

In my case, I’m running CentOS 6.7 in a virtual machine running on Oracle VirtualBox.

You should be able to get around the error pretty easily, just reboot the computer, and when you see the “Press any key to enter the menu” pictured below, press a key.

press-key1

You should be presented with a list of the kernels you have installed, pictured below, select the previous one, and press enter.

previous-kernel

After doing that I was able to boot into CentOS.

I did a little digging, and found this bug report, which matched my error, the only difference I can see is that the kernel version was different.

The first solution I ran across was to run “yum reinstall kernel”, which is what I did, and the issue was resolved. Evidently in some cases the kernel doesn’t fully install, and in some cases fails transaction checks.

If the reinstall doesn’t work for you, keep reading the comments, there’s several other solutions, hopefully one of them will help you out. Feel free to let me know what worked for you.

Good Luck!

How to Install Oracle VirtualBox Additions in Fedora 22

image

I’ve had to beat around the bush in past distros, and finally found a pretty straight forward way to get the VirtualBox Additions working on my Fedora Virtual Machines under Oracle Virtual Box. It’s handy because you get all the native mouse and display support. Here’s all you have to do.

Once you’re at the Fedora Gnome Desktop, click on Activities (or press the windows key on your keyboard) and type terminal. Then click on the terminal icon.

Quick note, they replaced yum with dnf, don’t panic, the yum command still work. Anyway …

Enter the following:

su

(type your password)

dnf -y update kernel*

dnf -y install kernel-headers kernel-devel dkms

Reboot

Insert the disk and run it.

VboxAdditions

You’ll have to enter a username and password.

When it’s all done, you should see something like this:

VboxAdditionsInstall

Then reboot again.

Fedora Replaced Yum with DNF ?!?!

First off, I was kind of shocked yesterday when I went to grab an ISO of Fedora 21, and realized that 22 had been released. I hadn’t read or seen anything that mentioned it was coming out. Not that I’m all the hyped up to grab the latest version or anything.

I guess it’s actually been coming for a long time, but I’m not very current on most Linux news. I personally prefer CentOS, but it seems like the only version of Linux that my coworkers use is Fedora, so that’s what I have to support. I guess I can count my blessings though, at least it isn’t Ubuntu 😉

The side benefit of this is that Fedora and CentOS are pretty close, so I don’t usually have to learn the commands / how to do things two different ways.

From the article linked above, it sounds like DNF is going to be better than YUM, and actually started out as a fork from Yum.

According to tecmint, DNF is going to replace yum in Centos and Redhat as well, so that works for me 🙂

What to do about Shell Shock (bash vulnerability)

One of my rules of thumb is that if a virus, worm, trojan, or other vulnerability has made it to the broadcast news, then it’s probably nothing to worry about anymore. I’ll have to say, I’m not sure how much longer that’s going to hold true. This morning Shellshock (officially it’s CVE-2014-6271) made the broadcast news, and it’s actually something that we should worry about.

When I say we, I mean we sysadmins / IT guys. Although … Continue reading What to do about Shell Shock (bash vulnerability)