As described in Message Delivery Modes. JMS defines two message delivery modes,
PERSISTENT and
NON_PERSISTENT, and EMS defines a
RELIABLE_DELIVERY mode.
NON_PERSISTENT and
RELIABLE_DELIVERY messages are never written to persistent storage.
PERSISTENT messages are written to persistent storage when they are received by the EMS server.
Persistent messages published to a topic are written to disk only if that topic has at least one durable subscriber or one subscriber with a fault-tolerant connection to the EMS server. In the absence of a durable subscriber or subscriber with a fault-tolerant connection, there are no subscribers that need messages resent in the event of a server failure. In this case, the server does not needlessly save persistent messages. This improves performance by eliminating the unnecessary disk I/O to persist the messages.
You can set the mode parameter to
sync for a given file storage in the
stores.conf file to specify that persistent messages for the topic or queue be synchronously written to disk. When
mode = sync, the persistent producer remains blocked until the server has completed the write-to-disk operation.