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At Wed, 3 Jun 2009 10:18:03 +0200, Hauke Fath 
<> wrote:
Subject: Re: NFS
> At 6:50 Uhr +0000 03.06.2009, David Holland wrote:
> >On Tue, Jun 02, 2009 at 04:47:08PM +0300, Jukka Marin wrote:
> >  > >  - are you using amd(8)? There is something wrong in that area...
> >  >
> >  > No.  (I never figured out how to use it ;)
> >
> >rm is the best way :-)
> At 16:14 Uhr -0400 02.06.2009, Greg A. Woods wrote:
> >BTW, I _never_ use AMD any more either -- besides just being generally
> >buggy and fragile in my experience,
> Ahh, nothing like a good bit of FUD in the early morning.
> Amd just works here on > 50 machines, and has so for years. YMMV, obviously.

I'll admit to having a relatively poor understanding of where AMD can
actually provide some of the benefits its proponents claim for it.  I
have an even poorer understanding of how it can interact badly with
various situations and cause problems.

However in particular I find it impossible to believe that it will make
NFS appear to be more reliable for even one or a very few mounts on one
client host.  More often than not the problems were caused by AMD, and
going to fixed NFS mounts solved those problems.  Sure it can refuse to
mount filesystems from servers that are not healthy and it can unmount
unused filesystems after some time, but that doesn't really help with
actual reliability.  It can also apparently use replicated servers
dynamically, but that's not part of the common claim about better
reliability for just one mount from one server.  It's a large amount of
quite complex code that I feel is best to avoid using if possible.

I'll also admit though that my past experiences with AMD were not with
NetBSD clients (or servers).  Perhaps some of my bad experiences with
AMD were due more to mis-configuration -- after all it is commonly said
that AMD can be very difficult to configure correctly.  All the times I
have encountered AMD, I was not responsible for its use or operation.
Some problems I remember, such as it unmounting filesystems which
actually were in use don't sound like they could be caused by
mis-configuration though.

Further I'll admit I've never built any network with a complex enough
mess of file servers to ever face any problems with manually maintaining
client system fstab entries.  Even with very large networks I've been
able to keep the number of NFS servers and mounts to a minimum.  I also
know to avoid using NSF on mobile clients.  :-)  I'd also say too that
there are far simpler ways to deal with automatic mounting of things
like removable media on workstations and the like.

My biggest problem with NFS without AMD are the times when I mount
filesystems from non-production machines and then don't remember to
unmount them when the machine is down.  Even then though the biggest
problems are with operations that _should_ be interruptable (when the
mount was done with "-i"), but which are not, most notably "df".
Hmmm.... doesn't seem like there's a PR open for that problem.

                                                Greg A. Woods
                                                Planix, Inc.

<>       +1 416 218-0099

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