Plasma & NFS

[test]

On Friday, May 29, 2020 5:23:42 PM CEST Alexander Puchmayr wrote:
> Hi there!
> 
> My Linux box has its home directories on a local SSD, and occasionally I
> need to mount the home directories of other machines (server, laptop(s),
> etc). When I do this and forget to unmount them, plasma gets stuck and is
> no longer responsive. Kwin seems to work, but switching activities does
> not. The Sidebar also gets stuck, I cannot launch applications anymore. In
> other words: The desktop is almost frozen because it waits for a NFS share
> to response that is actually not needed at all for the desktop to work.
> 
> Why is that behavior? I understand that a dolphin window may freeze if the
> directory it shows is no longer available, but why the whole desktop?
> 
> Is there anything I can do against this?
> 
> Thanks
> 	Alex

Parts of kde --- and more or less all other programs you may have running --- 
store files in your home directory, so you _must not_ suddenly unmount your 
home directory.  If you mount it so that I/O operations can be interrupted and 
interrupt them, you are likely to experience data loss and/or crashing 
programs.  It's virtually the same as if someone pulls the chair from under 
you right when you're about to sit down.

If you really want to unmount your home directory and mount another one 
instead, make sure that no files are open and that no programs are running 
that might want to access files there.  When using KDE, that means you need at 
least to log out before unmounting, and you may even need to reboot.

Keep your home directory on the local disk and mount the other file systems 
you need to access on directories under /mnt and use symlinks as needed, and/
or use autofs.

KDE with home on NFS is rather slow anyway; there's just no way that you could 
beat the low latency of SSDs or local hard disks with that, unless perhaps if 
you have 10Gb ethernet links.  Besides being to use my workstation without 
depending on another machine being available, the slowness is the main reason 
that I switched from home on NFS to home on local disks (after switching from 
fvwm to KDE).

You may be able to get away when using fvwm (i. e. the responsiveness will be 
bearable), but not keeping the home directory steady will remain a hassle 
nonetheless.  It's a really bad idea I wouldn't even consider.

It's like creating intentionally creating disk failures.  Don't do it.