When changes are made to objects within a partition, those
changes are automatically sent to all other replicas of that partition.
This ensures that the global Directory database remains consistent.
Only changes are sent to other replicas. For example, if a user
changes a phone number, only the new phone number is sent, not the
entire User object.
An NDS database is a "loosely consistent"
database. As changes occur, all replicas of a partition do not always
contain exactly the same information at every instant. In fact,
the contents of the replicas most likely vary slightly at any given
time. However, these replicas eventually converge to a consistent
state once the changes are distributed to all replicas.
Some changes are sent immediately to other replicas, such
as changes to a user's password. Other, less critical changes,
such as a user's last login time, are collected locally
for a short period of time before being sent out to the network.
Every partition maintains a record of its replicas. The locations
are stored in the partition's replica property, with one
entry for each replica. The collection of replica properties of
a partition forms a list of the replicas, sometimes called a replica ring or replica list.
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