Re: Instability with NetBSD Dom0

[tg%gmplib.org@localhost (Torbjörn Granlund)]

Greg Troxel <gdt%ir.bbn.com@localhost> writes:

  The only thing I can think of is that there at least used to be problems
  with sparse files.  I use dd to create image files, with if=/dev/zero
  and fill in the file entirely.  I don't know exactly what qemu-img-xen
  does.
  
  I wonder if you are having a filesystem locking bug problem, rather
  than a xen problem.

This actually sounds like a plausible explanation.  Thank you!

I've seen Dom0 CPU usage go up inexplicably for certain DomU file
operations.  Usually the systems stabilise after having been frozen for
perhaps a dozen seconds.  I recall that I some years ago stopped using
sparse files under NetBSD, but I cannot recall the details of what led
me to do that.

The new disastrous problem happened when I used a 20 GB sparse file
(yes, qemu-img-xen creates sparse files); all images used for this
system were just 1 GB to 2 GB.  Perhaps size matters?

I'll try and find time for some experiments.  (I will need to remove the
system from the co-location site.)


-- 
Torbjörn
Please encrypt, key id 0xC8601622