Subject: [nfsv4] Fwd: feedback from the ldap community on NSDB replication semantics

From: "Daniel Ellard" <[email-masked]>
Date: Mon, 1 Dec 2008 10:38:59 -0500

Whoops, meant to press "reply-all" instead of "reply".

On Mon, Dec 1, 2008 at 3:49 AM, Leif Johansson <[email-masked]> wrote:

> ...
> This means that there is very little chance that the LDAP community will
> grow a new replication semantics any time soon. This leaves the following
> alternatives for NSDB (afaiu):
>
> 1. Avoid the problem: rewrite the specifications to remove the requirement
> on strict transactional semantics for NSDB update operations.
>
> 2. Handwave: Write text in the specifications that explains the limitations
> on deployments imposed by the LDAP replication semantics.
>
> 3. The hard way: Don't use LDAP at all.
>
> I guess 3 is out of the question and 1 may be quite difficult. Let me
> explain what I mean by 2: In most "sensible" deployment scenarios the
> LDAP  replication semantics may be "good enough" in the sense that the
> user probably won't notice anything.

I'm not at all surprised.  It was optimistic to expect anything else.

#3 has been on the table before, and could make a comeback.  The actual
protocol we need is so small and simple that replacing LDAP with something
simpler but based on and conforming to well-known and established specs
(i.e., RPC/XDR/GSS) would not be a daunting task.  (and the particular case of
RPC/XDR/GSS is something that folks in the NFS world are already dealing
with)

We originally went with LDAP over some alternatives because it looked
like it would make our lives easier: Glamour already used it, and it's
fairly portable.  If it's failing to make our lives easier, then let's revisit
the decision.  HOWEVER, in order to prevent stalling the entire process
for months while we backtrack on this, I suggest that the current LDAP-based
protocols still be used for proof-of-concept work.

Also, I think the distinction between #1 and #2 is so subtle to be nearly
unimportant.  (or maybe I don't fully understand it)  We need a best-practice
guide in any case, because no matter how we implement this thing, there
will be bad ways to configure it.  Call it handwaving if you prefer, but we
have to call out the limitations of any approach.

-Dan
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From: Leif Johansson <[email-masked]>
Date: Mon, 8 Dec 2008 19:52:01 +0100

> unimportant.  (or maybe I don't fully understand it)  We need a
> best-practice guide in any case, because no matter how we implement this
> thing, there will be bad ways to configure it.  Call it handwaving if you
> prefer, but we have to call out the limitations of any approach.

For the record I think there are significant differences - either you are fine 
with the LDAP semantics or you're not but can deploy LDAP in such a way
that you avoid hurting yourself too much in practice.

	Cheers Leif