Replication terminology
Some terminology used in describing replication:
- Cascading replication
- A replication topology in which there are multiple tiers of
servers. A peer/master server replicates to a set of read-only (forwarding)
servers which in turn replicate to other servers. Such a topology off-loads
replication work from the master servers.
- Consumer server
- A server which receives changes through replication from another
(supplier) server.
- Credentials
- Identify the method and required information that the supplier
uses in binding to the consumer. For simple binds, this includes the DN and
password. The credentials are stored in an entry the DN of which is specified
in the replication agreement.
- Forwarding server
- A read-only server that replicates all changes sent to it by a master
or peer. Client update requests are referred to the master or peer server.
- Gateway server
- A server that forwards all replication traffic from the local replication
site where it resides to other gateway servers in the replicating network.
A gateway server receives replication traffic from other gateway servers within
the replication network, which it forwards to all servers on its local replication
site. Gateway servers must be masters (writable).
- Master server
- A server which is writable (can be updated) for a given subtree.
- Nested subtree
- A subtree within a replicated subtree of the directory.
- Peer server
- The term used for a master server when there are multiple masters for
a given subtree.
- Replica group
- The first entry created under a replication context has objectclass
ibm-replicaGroup and represents a collection of servers participating in replication.
It provides a convenient location to set ACL's to protect the replication
topology information. The administration tools currently support one replica
group under each replication context, named ibm-replicagroup=default.
- Replica subentry
- Below a replica group entry, one or more entries with objectclass ibm-replicaSubentry
can be created; one for each server participating in replication as a supplier.
The replica subentry identifies the role the server plays in replication:
master or read-only. A read-only server might, in turn, have replication agreements
to support cascading replication.
- Replicated subtree
- A portion of the DIT that is replicated from one server to another.
Under this design, a given subtree can be replicated to some servers and not
to others. A subtree can be writable on a given server, while other subtrees
might be read-only.
- Replicating Network
- A network that contains connected replication sites.
- Replication agreement
- Information contained in the directory that defines the 'connection'
or 'replication path' between two servers. One server is called the supplier
(the one that sends the changes) and the other is the consumer (the one that
receives the changes). The agreement contains all the information needed
for making a connection from the supplier to the consumer and scheduling replication.
- Replication context
- Identifies the root of a replicated subtree. The ibm-replicationContext
auxiliary object class can be added to an entry to mark it as the root of
a replicated area. The replication topology related information is maintained
in a set of entries created below a replication context.
- Replication site
- A Gateway server and any master, peer, and replica servers configured
to replicate together.
- Schedule
- Replication can be scheduled to occur at particular times,
with changes on the supplier accumulated and sent in a batch. The replica
agreement contains the DN for the entry that supplies the schedule.
- Supplier server
- A server which sends changes to another (consumer) server.