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Date:      Thu, 6 Jan 2011 07:58:55 -0500 (EST)
From:      Rick Macklem <rmacklem@uoguelph.ca>
To:        perryh@pluto.rain.com
Cc:        marek sal <marek_sal@wp.pl>, freebsd-stable@freebsd.org, milu@dat.pl, jyavenard@gmail.com, jhb@freebsd.org
Subject:   Re: NFSv4 - how to set up at FreeBSD 8.1 ?
Message-ID:  <1301662185.172571.1294318735174.JavaMail.root@erie.cs.uoguelph.ca>
In-Reply-To: <4d258100.Wu9WZrgdH2/KvDTa%perryh@pluto.rain.com>

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> Rick Macklem <rmacklem@uoguelph.ca> wrote:
> 
> > Sun did add a separate file locking protocol called the NLM
> > or rpc.lockd if you prefer, but that protocol design was
> > fundamentally flawed imho and, as such, using it is in the
> > "your mileage may vary" category.
> 
> I suppose it was not all that bad, considering that what it sought
> to accomplish is incomputable. There is simply no way for either
> the server or the client to distinguish between "the other end has
> crashed" and "there is a temporary communication failure" until the
> other end comes back up or communication is restored.
> 
Yep. The blocking lock operation is also a trainwreck looking for a
place to happen, imho. (In the NLM, the client can do an RPC that says
"get a lock, waiting as long as necessary for it, and then let me know".)

> On a good day, in a completely homogeneous environment (server and
> all clients running the same OS revision and patchlevel), I trust
> lockd about as far as I can throw 10GB of 1980's SMD disk drives :)
> 
Heh, heh. For those too young to have had the priviledge, a 1980s SMD
drive was big and HEAVY. I just about got a hernia every time one had
to go in a 19inch rack. You definitely didn't throw them far:-)

> Exporting /var/spool/mail read/write tends to ensure that good days
> will be rare. Been there, done that, seen the result. Never again.
> That's what IMAP is for.
> 
Great post. I couldn't have said it as well, rick



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