Posted by & filed under Server Admin.

UPDATE 11/17/15: Another nice command to auto purge old kernels is: sudo apt-get autoremove

 

Also, removing old kernels is easy with  sudo dpkg -r linux-image-3.2.0-83-generic

—————————

 

Recently I wanted to install a new package on a Ubuntu server. Typically this is as simple as issuing a

But this time around, I got a interesting error:

I started poking around and found that the /boot partition is full:

Ok, that is starting to make a bit more sense now… so we need to purge old kernel packages to free up space on the /boot partition. The first step is to identify the kernel version we are currently on so we do not delete that. Secondly, it was recommended to me that you keep the oldest kernel as it was the one the system was installed with. We can see the kernel version with:

So we are on 3.0.0-25-server and need to make sure not to delete that. A handy command to get a list of all the kernels you are not using is:

I attempted to remove old kernels the “nice” way — by letting apt handle the removal:

But it failed. Following the above instructions to run sudo apt-get -f install, it failed saying that there was not enough disk space on /boot (duh!). So much for being nice.

Inside the /boot partition there are three “types” of files — abi-kernel-version, config-kernel-version, initrd.img-kernel-version, System.map-kernel-version, vmcoreinfo-kernel-version, and vmlinuz-kernel-version. There will be a file for each of these for each version of the kernel you have installed. For example: vmlinuz-3.0.0-28-server. Leaving the earliest kernel version and the version I am running (reported by uname -a), I moved the other kernel files off to another location where there was ample space. It looked something like this:

As you can see this is moving the files for kernel version 3.0.0-16 off the /boot partition.

If the boot partition just needed a bit of space freed up, you can now likely use apt-get to purge the other kernels “cleanly”. What I mean by that is apt-get also removes the kernel files from /lib/modules. You could do this by hand as well. I am not sure if it does anything beyond cleaning up /boot and /lib/modules, but I do not believe it does.

Leave a Reply

You must be logged in to post a comment.