Last night my main computer with Linux Mint 20 crashed and I was really worried that I might lose the files I had been working on. After many google searches, I found a solution and knew why it happened.
The computer did not respond to mouse or keyboard input so I had to hold down the power key for a few seconds to shut it off. When the computer restarted, it showed the Linux Mint login screen but the system did not let me log in. I tried a few times entering my password and also tried to restart the computer, but still could not log in.
After some google searches, I found this online post
I followed the answer by Lohengrines, did the following steps, and logged into the system.
sudo tune2fs -m0 /dev/sda2
There were previous discussions on the same topic on Linux Mint Forum. This post had more information.
As suggested on the above post, when I ran the command
df -h sudo du -h -d 1 / | sort -n # this is for 1 level of dir under root /
I found two huge files under /var/log directory. It turned out that both
kern.log files were of 40GB+ sizes. And the disk was full and
that was the reason I could not login.
Unfortunately I could not simply delete those two files. How to remove them? There was another post for that.
The following command cleared the two files to 0 byte:
sudo su > /var/log/syslog > /var/log/kern.log
After that the disk showed a free space of 90GB. I also ran the command below to change the reserved disk blocks percent back to 5 percent.
sudo tune2fs -m5 /dev/sda2
I have a large 30 inch Dell U3011 monitor I bought a few years ago. The desktop connects to the monitor via a displayport cable. I also connect my laptop to the monitor through the same cable. I simply unplug the cable from desktop and plug it to the laptop.
Last night, I did not turn off the desktop when unplugging the monitor cable. Linux Mint 20 system started outputting the same error messages again and again. It eventually filled up the disk. That was the reason I could not log into the system. Though it was painful, I did learn something from this crash experience.
Update (9/24/2020): The computer crashed again today and the reason I wrote above
was not correct. I added a
maxsize 10M setting to the configuration file following
I also updated the system to the latest.