Novell EDIRECTORY 8.8 SP3, Administration Manual, Page: 57 / 634

Understanding Novell eDirectory 57
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Read/Write Replica
Description: Read-Write Replica icon eDirectory can access and change object information in a
read/write replica as well as the master replica. All changes are then automatically propagated to all
replicas.
If eDirectory responds slowly to users because of delays in the network infrastructure (such as slow
WAN links or busy routers), you can create a read/write replica closer to the users who need it. You
can have as many read/write replicas as you have servers to hold them, although more replicas cause
more traffic to keep them synchronized.
Read-Only Replica
Description: Read-Only Replica icon The read-only replica is a readable replica type used to
read information about all objects in a partition’s boundaries. Read-only replicas receive
synchronization updates from master and read/write replicas but don’t receive changes directly from
clients.
This replica type is not able to provide bindery emulation, but it does provide eDirectory tree fault
tolerance. If the master replica and all read/write replicas are destroyed or damaged, the read-only
replica can be promoted to become the new master replica.
It also provides NDS Object Reads, Fault Tolerance (contains all objects within the Partition
boundaries), and NDS Directory Tree Connectivity (contains the Partition Root object).
A read-only replica should never be used to establish a security policy within a tree to restrict the
modification of objects, because the client can always access a read/write replica and still make
modifications. There are other mechanisms that exist in the directory for this purpose, such as using
an Inherited Rights Filter. For more information, see
“Inherited Rights Filter (IRF)” on page 65 .
Filtered Read/Write Replica
Description: Filtered Read-Write Replica icon Filtered read/write replicas contain a filtered set
of objects or object classes along with a filtered set of attributes and values for those objects. The
contents are limited to the types of eDirectory objects and properties specific in the host server's
replication filter. Users can read and modify the contents of the replica, and eDirectory can access
and change selected object information. The selected changes are then automatically propagated to
all replicas.
With filtered replicas, you can have only one filter per server. This means that any filter defined for
a server applies to all filtered replicas on that server. You can, however, have as many filtered
replicas as you have servers to hold them, although more replicas cause more traffic to keep them
synchronized.
For more information, see “Filtered Replicas” on page 58 .
Filtered Read-Only Replica
Description: Filtered Read-Only icon Filtered read-only replicas contain a filtered set of objects
or object classes along with a filtered set of attributes and values for those objects. They receive
synchronization updates from master and read/write replicas but don’t receive changes directly from
clients. Users can read but not modify the contents of the replica. The contents are limited to the
types of eDirectory objects and properties specific in the host server's replication filter.
For more information, see “Filtered Replicas” on page 58 .