Terminology for replication

Howard C. Berkowitz hcb at clark.net
Sat Jun 13 15:39:33 UTC 1998


In determining customer requirements for "multihomed" or generic
high-availability services, I often find there is a major terminology
problem.  Customer expectations may not be met because they are using
"cache" or "mirror" differently than an ISP person.

After the April IETF meeting, Jacob Palme posted to the general IETF
mailing list what I tink is an excellent start on the problem.  There was
almost no response, other than a comment or two that different application
communities use the terms differently.

Perhaps these issues would be more of interest in NANOG, because I think
they are very operational at the requirements definition end.   Unless a
more useful place to collect comments emerges, I'd like to record the
consensus in my I-D on multihoming requirements, currently
http://www.ietf.org/internet-drafts/draft-berkowitz-multirqmt-01.txt
My thoughts would to be to get one more round of comments, see if the IETF
Operations Area wants to consider it, and if not send it to the IESG as an
individual contribution in a month or two.  The subject is one of those
things that doesn't quite fit the RFC model.

-----------
Date: Thu, 2 Apr 1998 15:38:13 +0100
To: IETF general mailing list <ietf at ns.ietf.org>
From: Jacob Palme <jpalme at dsv.su.se>
Subject: Terminology for replication

What is the correct term for various kinds of replication. Below is a
proposal as a basis for a discussion.

Function						Proposed term
-------------------------------------------------------+-------------------
A general term for all kinds of copying of identical	Replication
to several stores.

Replication, where the stores which hold the ori-	Mirroring
gal knows about where copies are held and periodic      (I have also heard
automatic updates ensure conformance between mirror     the term push-
copies and the original.				caching)

Replication, where a store saves a copy of a docu-      Caching
ment which it happens to get, without 100 % safe
methods against outdated objects in the cache.

Caching with some added facilities, such as		Controlled caching?
"Expiry" fields, to reduce the risk of outdated
objects in a cache.

Replication, where all copies are equally valid,        ?????
none of them is the "original", as in Usenet News.

------------------------------------------------------------------------
Jacob Palme <jpalme at dsv.su.se> (Stockholm University and KTH)
for more info see URL: http://www.dsv.su.se/~jpalme





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