Kubuntu 18.04 crash and only black screen on reboot

[Dr Diamante]

Hello all,

I just installed Kubuntu 18.04 on a 64gb partition without a SWAP partition in the same HD as apparently, Kubuntu uses a SWAP file instead. The machine has 64gb of RAM memory. However, after 1:30hs using a 3D software in Kubuntu, the machine crashed and every time that i reboot now i just see a black screen with the mouse cursor on the middle, i can move the cursor but nothing hapenns.

That said, do i need to create a SWAP partition even though the machine has 64gb of RAM and re-install Kubuntu18.04?

Any help is appreciated. Thanks.

[GreyGeek]

Your 3D software probably uses the swap file and ran out of room.
I would definitely remove the swapfile and make a swap partition equal to your RAM size plus a little. Probably around 66GB or so.

[jlittle]

I suggest:

• Back up any important data; to get to it you might have to boot to live USB, or the recovery console.
• Boot to the recovery console, and check the free space on the root file system. If there isn't any, that's good, you know why KDE won't start. I'd try to find a culprit; suspecting a swap file seems very reasonable to me but that's outside my experience, I've always had a swap partition. I don't know if recovery mode uses swap; if it does I think the swapoff command will stop that. If you want to make changes, like deleting something, the root file system will have to be remounted in read/write mode.
• If the recovery console doesn't work, or you don't like it, booting to a live USB might let you find out what's happened and maybe fix it.
• I'd try to find out what the 3D software recommends for memory and swap; but I wouldn't try too hard, such recommendations get out of date quickly.
• When you get Kubuntu running again, use KSysGuard or a panel widget to check memory and swap use as you work.

Regards, John Little

[Dr Diamante]

Thanks for the info @GreyGeek and @jlittle.

I managed to get Kubuntu running again after cleaning and removing the older kernel installed and some little package installers. In recovery mode, i ran these commands:

sudo apt-get autoclean

and then

sudo  apt-get autoremove

However, i noticed that for some reason, as soon as i reboot the system i see that 137 packages were installed and only 2gb were available in the 64gb partition where the swap file is also saved. After 25 mins using the machine, 145 packages were running and counting. Given the fact that i had only used the partition with the new OS for 28hrs, it doesn't make sense to have the packages been installed in the background without any notification. Now i don't know how to stop the auto install neither the auto update. I suspect that this could be the reason why Kubuntu crashed.

Any suggestions on how to stop the packages auto install?

I'm really considering re-creating a bigger partition to run Linux, maybe 100gb and then add a swap partition of 66gb as @GreyGeek mentioned, just to be safe. I'm back to the drawing board.

Best.

[GreyGeek]

The system monitor shows that I have, at the moment, 236 processes and apps running, so 145 isn't excessive.
But if you have only 2GB of free space left then your system is going to start experiencing slowdowns.

Normally, 60+GB for Kubuntu (or Linux in general) isn't too small and things run fine, but I've never used a machine with 64GB of RAM.

Seems like 100GB would be better in your case, but I'm just guessing.

[Dr Diamante]

After following your suggestion, apparently things are running fresh an smooth now.

I re-created a new partition with 100gb and allocated 70gb for the swap and the rest for the installation. I re-installed Kubuntu, re-installed the latest nvidia driver and everything seems to be smoking fast now.

Thank you for the help GreyGeek! Nothing like wisdom.