8.4.1. Understanding Replicator States
Each node within the cluster will have a specific state that indicates
whether the node is up and running and servicing requests, or whether
there is a fault or problem. Understanding these states will enable you
to clearly identify the current operational status of your nodes and
cluster as a whole.
A list of the possible states for the replicator includes:
The replicator service is starting up and reading the replicator
properties configuration file.
The node has been deliberately placed into the offline mode by an
administrator. No replication events are processed, and reading or
writing to the underlying database does not take place.
The node has entered the offline state because of an error. No
replication events are processed, and reading or writing to the
underlying database does not take place.
The replicator is currently reading provisioning information from
the master database before entering the
The replicator is preparing to go online and is currently restoring
data from a backup.
The replicator is preparing to go online and is currently preparing
to process any outstanding events from the incoming event stream.
This mode occurs when a slave has been switched online after
maintenance, or in the event of a temporary network error where the
slave has reconnected to the master.
The node is currently online and processing events, reading incoming
data and applying those changes to the database as required. In this
mode the current status and position within the replication stream
is recorded and can be monitored. Replication will continue until an
error or administrative condition switches the node into the
The replicator is processing any outstanding events or transactions
that were in progress when the node was switched offline. When these
transactions are complete, and the resources in use (memory, network
connections) have been closed down, the replicator will switch to
OFFLINE:NORMAL state. This
state may also be seen in a node where auto-enable is disabled after
a start or restart operation.
In general, the state of a node during operation will go through a
natural progression within certain situations. In normal operation,
assuming no failures or problems, and no management requested offline, a
node will remain in the
Maintenance on Tungsten Replicator or the dataserver must be performed
while in the
OFFLINE state. In the
OFFLINE state, write locks on the
THL and other files are released, and reads or writes from the
dataserver are stopped until the replicator is