[ENBD] A comparison of ENBD and DRBD, updated

[Peter T. Breuer]

"A month of sundays ago Richard Sharpe wrote:"
> My setup is a Dual-celeron 533 as the source and an AMD K6-2/400 as the
> sink, with a 100Mb/s ethernet between the machines (crossover cable).

What kernel? NBD is only certified for 2.2 kernels.

> My first problem was getting ENBD to run at all on the SMP machine. It
> required a small hack on the Makefile to pass -DSMP or -D__SMP__ to all
> compiles. I used Version 2.2.7 of ENBD.

THis is very unsafe. 2.2.28 is the current stable version and 2.4.14
is the recommended one. And yes, you need to pass -D__SMP__ to compile
for SMP.

> Once I got it going, I found that I could I could write small files to the
> network device, /dev/nda, but if I tried to write a large file, like 100MB,
> it hung. I hope to give it another try soon.

NBD sees no difference between small or large files. It works at the
block layer. I suspect some unknown cockpit error by user :-). The
behaviour sounds like what one would get using a 2.4.0t1 kernel. But to
be sure that it's not an SMP issue (I don't have an SMP testbed), run with
only one client daemon and client connection so that accesses are serialized.

Peter