Re: How do I stop system hangs?

["Alexander V. Makartsev" <avbetev@gmail.com>]

On 05.11.2017 11:54, Borden Rhodes wrote:

...

I checked the hard drive using the manufacturer's diagnostics and it's
fine. Even if the hard drive were failing, I'm not sure how it would
address my question. Shouldn't enough of the operating system be
running in RAM (I have 4 gigs of it and no swap) so that my computer
can switch to and log into a terminal without needing to access the
hard drive?

The situation you describe would seem like a perfect use case for the
solution I'm looking for: hard drive is going fritzy, so instead of
yanking the plug or letting Linux torture the drive to death, let the
user go into a shell and stabilise the system long enough to shut it
down, back up data or do something else.

So, back to my original question: How do I tell Linux to keep
resources available, ideally in RAM, so I can switch into a different
terminal if my desktop hangs and recover the system?

With thanks,

For now you just assuming your system has resource starvation and it causes system to hung. You have no evidence to prove that, do you? You also didn't posted anything about your hardware and software setup, only mentioned 4Gb of RAM and that is a plenty for casual PC to function normally.
You can check syslog from previous hung session after reboot with:
    $ sudo systemctl -b -1

With failing hardware you can't do anything. Like you can't recover from Kernel Panic/OOPS or BSOD.
"manufacturer's diagnostics" software in my experience never were good enough to tell about failing drive right away, only when it is already obvious.
You have to use tools I mentioned at least, to scan every surface block and check SMART table inside your disk's firmware.

-- 
With kindest regards, Alexander.

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