Local queues and asynchronous remote queues store messages and therefore have properties to determine how and where the messages are stored.
The message store determines how the messages are mapped to the storage medium. The C and Java versions of WebSphere MQ Everyplace support a default message store, allowing long file names. The Java version of WebSphere MQ Everyplace has two additional message stores, MQeShortFilenameMessageStore that ensures the file name does not exceed eight characters, and the MQe4690ShortFilenameMessageStore that supports the default file system on a 4690. A storage adapter provides the message store access to the storage medium, the Java and C versions of WebSphere MQ Everyplace provide disk adapters with the Java version also providing a case insensitive adapter and a memory adapter.
The backing store used by a queue can be changed using a WebSphere MQ Everyplace administration message. Changing the backing store is not allowed while the queue is active or contains messages. If the backing store used by the queue allows the messages to be recovered in the event of a system failure, then this allows WebSphere MQ Everyplace to assure the delivery of messages.