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

From: Leif Johansson <[email-masked]>
Date: Mon, 1 Dec 2008 09:49:02 +0100

I've brought up the subject of the NSDB transactional requirements on  
[email-masked] where most ldap vendors sit. I asked how they would 
respond to an extension that modifies the transactional semantics of 
a write operation. 

The response was overwhelmingly negative suggesting that this approach
is probably doomed to failure in the IETF and would never get implemented
by most vendors - it seems strict distributed transactions would be very
difficult to implement in most vendors products.

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. 

However there are any number of ways to deploy LDAP (replication over 
slow or congested links, etc) that will make the problem appear more often. 

Doing 2 involves writing text about how to deploy LDAP for NSDB in order 
to make problems resulting from replication inconsistencies less likely to
appear in practice.

	Cheers Leif
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