system freezes

[Xen]

So I have a number of unknowns:



  - nvidia RAID (works fine in Windows)




  - LVM dm-cache of the root device

What happens is at least the following:

  - keyboard repetition regularly stops

  - the entire KDE environment sometimes freezes, sometimes it recovers, 
sometimes it doesn't.

  - it will freeze upon writes (saves)
  - last time the application successfully exited while saving but the 
KDE screen was frozen


  - but sometimes it also freezes while I'm not doing anything in 
particular.

Sometimes /etc/init.d/sddm restart works, sometimes it doesn't.

Sometimes ctrl-alt-f1 responds instantly, sometimes it takes a minute.

It seems more a KDE issue than anything else honestly.


Since this is a 4.10 kernel, the GTX 950 that is running inside, is 
supported by Nouveau.

Currently don't have broadband internet so I can't go and download big 
things.

I haven't checked top yet (for cpu consumption)

but

vmstat -d shows nothing unusual (as in queues)

Also there appear to be no messages in the console but I guess those 
only appear when you are in it?

Fairly annoying.

I mean the nVidia raid appears to be not entirely stable (in Linux)

But that thing only crashed once thus far while heavy writing :p.

I have no clue what could be causing it this time, I guess this is more 
a Kubuntu question than anything else,

but quite a bit annoying, let's just say debilitating.