My view of the terms involved:
Mirroring: The replication of a service or information set to another
server/location.
Replication: The act of copying a information entity to another location
on a regular basis (sheduled or on demand). The definition of a entity
ranges from a single file or record to a whole database depending on
system and design.
Replica: A copy of a information entity. Changes are propagated thru
replication.
Caching: Storage of server responses which is then substituted as
replies to later queries for the same entity.
Service replication: Broader concept of having multiple points of
precense for a service. Can be acheived thru replication, caching or
both, whichever seems most suitable for the service and purpose.
In my world the main difference between a replica and a mirror is
consistency. A mirror can (intentionally or accidently) diverge somewhat
from the original, while a replica must be a exact copy at the time the
replica is made or at least be able to tell what is not. Replication can
also be two-way while mirroring is always a one-way relation.
A example of a intentionally diverged mirror is where part of the
information contained in the mirror is not replicated from a origin
source but produced locally for the specific mirror.
-- Henrik Nordstrom
This archive was generated by hypermail 2b29 : Thu Nov 18 2004 - 11:21:26 MST