Anyone putzing with NBD besides me?

G.W. Wettstein (greg@wind.enjellic.com)
Tue, 28 Sep 1999 10:14:19 -0500


Good morning to everyone on the list.

Is anyone working with the Network Block Device driver (NBD) in
2.2.12. If so what type of luck are you having.

I grabbed the tarball of userland stuff from Pavel's site and have it
up and running between a couple of SMP dual PII-450 systems. I can
make a filesystem on the device and mount it and read/write files just
fine.

Problems seem to occur when the device gets subjected to large amounts
of I/O. In these cases the throughput goes way, way done. The
slowdown can be pretty easily demonstrated by running Bonnie with a
scratch filesize of 200-300 megabytes.

It smells like a client side (NBD) problem and it also appears to be a
Heisenbug. When I turned on debugging in the server side utility the
stalls went away but throughput was than poor due to the massive
amounts of I/O being generated in the way of the debug information
being printed.

I would be interested in the experiences that anyone has had or if there
are a set of patches floating around which improve performance.

Thanks much and have a pleasant mid-week.

Greg

As always,
Dr. G.W. Wettstein Enjellic Systems Development - Specializing
4206 N. 19th Ave. in information infra-structure solutions.
Fargo, ND 58102 WWW: http://www.enjellic.com
Phone: 701-281-4950 EMAIL: greg@enjellic.com
------------------------------------------------------------------------------
"A distributed system is one on which I cannot get any work done because
a machine I have never heard of has crashed."
-- Leslie Lamport

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